Hockey Analytics: What Does It Mean For Cornell?

Since I've been on the advanced stats thing a lot recently, I just want to bring up a graphic from SB Nation Blog Eyes on the Prize that shows why puck possession matters, exactly how good a proxy these advanced stats are for possession, and how strongly possession correlates to winning. I've mostly talked Corsi here because it is easier for me to estimate with the less detailed stats that are kept in college hockey. However, of the advanced statistics that have been developed, no statistic seems to have more predictive value toward winning than Fenwick Close %. I am presenting them up front, for those who do not want to read the long winded explanation of advanced stats below, but maybe the images will intrigue you enough for the the TL;DR part.

Playoff Teams since 2007-2008


Non-Playoff Teams since 2007-2008


For those who have not really looked into advanced stats yet, Fenwick is like Corsi in that it is a +/- type statistic that accounts for shot attempts in a given situation during a game. However, there are important differences between the two statistics. Unlike Corsi, which accounts for ALL shot attempts, Fenwick eliminates blocked shots from the equation, presumably under the logic that shot blocking is a skill, not a random event.

It is always important regarding this statistics to be aware of the game situation, and other contextual factors that can contribute to results, and as a result hockey analysts have developed a wide array of variants on Fenwick and Corsi that attempt to isolate these contextual factors. There are separate Fenwick and Corsi stats for different game situations, such as 5 v 5, the power play, the kill, 5 v 3, etc. Both statistics can also be presented as a percentage, but this eliminates some context, for example Cornell can dominate possession without taking a ton of shots attempts if it is very successful at eliminating shots by the opponent. The context is valuable because it can give you hints at how a team plays, but it is not really necessary to the predictive value of the statistic. The same goes for statistics such as CorsiFor and CorsiAgainst, which will tell you the context of offensive style or defensive style (i.e. is one team a Guy Godowsky team that just throws pucks at net inflating their CorsiFor number, or is their positive Corsi coming from a stifling defense and a low CorsiAgainst like the clutch and grab era Devils had).

One other major matter of context that should be noted is that score effects manipulate the strategies each team takes. A team that is trailing is more likely to take a ton of shots than the typical Cornell team that has a 2 goal lead in the third. These score effects can bias the results of advanced statistics if we don't account for the game context in which particular events occurred. This is where the close portion of the statistic that this graphic presents comes into play. Puck possession ability is usually most accurately represented by team strategies in close games while playing at even strength. In this context, close is defined as when teams are within one goal during the first or second periods, or tied in the third period or overtime. This is not only the largest sample of game events, as more minutes in hockey are played at even strength in close situations than any other context, but the results are also less biased by changes in team strategy, such as reverting into a neutral zone trap and dumping the puck for the last period of the game, because you no longer need to score.

So Fenwick Close % is essentially the percentage of all unblocked shot attempts your team gets when the game is within one goal before the third period starts, and while tied after the third period begins. The graphics above show that teams that thrive and dominate puck possession in these situations have wildly successful over the past 5 years. As I've mentioned before, and the Habs blog mentioned in their article, a short season, such as the one played in college hockey, or the lockout shortened 2012-2013 season may be short enough to see some statistical oddities and teams get lucky, but over the course of time, teams that have the puck win, and they win a lot.

This weekend was great because its the first time all season that we seemed to play really well at even strength.I'd call the win over Brown nothing short of dominant, which is what this team should be doing to bad teams, and the game against Yale was a very good game against a very good team. Did we dominate Yale? I don't really have the numbers, but I'd say the game looked fairly even to me. The biggest difference was that on our huge rebound Knisley happened to be standing in the net, while on Yale's huge rebound the play came out flat to Lowry's stick and no one was in the way. Hockey has a large element of chance to it, so its best to be the team with more balls in the lottery so to speak. Either way, hopefully we keep dominating possession against two bad teams the next two games and more importantly get results out of both games. Teams with the puck win games and this weekend was a good start.

For anyone interested in learning more on advanced stats, I highly recommend checking out the writing at Broad Street Hockey, Raw Charge, or Arctic Ice Hockey as jumping off points. Apologize for the long post, but I figure it was useless without some context.

css228
Apologize for the long post, but I figure it was useless without some context.

Don't apologize, this is great stuff. Thank you for taking the time to write it out clearly.

I haven't followed the other links (I will), but the first thing that I wondered was is there any reason to believe puck possession is causal of success, as opposed to being simply correlated because both puck possession and success are caused by an independent variable (namely, having better players)? It does not seem like a team can simply decide they are going possess the puck more. Possession seems dependent on other things that are more in the power of the team (well, the coach) to control: recruiting for and exercising to improve strength, size, speed, conditioning, as well as some skills that are second-order effects of those things: winning the battle in the corners, beating the opponent to the puck, passing crisply, staying above the opponent.

Or are you saying that some team strategies and in-game tactics stress possession over other goods and this is disproportionately successful? Is stressing possession a disputed notion?

Trotsky

css228
Apologize for the long post, but I figure it was useless without some context.

Don't apologize, this is great stuff. Thank you for taking the time to write it out clearly.

I haven't followed the other links (I will), but the first thing that I wondered was is there any reason to believe puck possession is causal of success, as opposed to being simply correlated because both puck possession and success are caused by an independent variable (namely, having better players)? It does not seem like a team can simply decide they are going possess the puck more. Possession seems dependent on other things that are more in the power of the team (well, the coach) to control: recruiting for and exercising to improve strength, size, speed, conditioning, as well as some skills that are second-order effects of those things: winning the battle in the corners, beating the opponent to the puck, passing crisply, staying above the opponent.

Or are you saying that some team strategies and in-game tactics stress possession over other goods and this is disproportionately successful? Is stressing possession a disputed notion?

The major reason to believe that puck possession is causal is that it seems as though shot quality, in the sense of taking few shots but regularly creating better quality chances isn't a repeatable phenomenon. Goals are a sufficiently rare event that they are highly effected by chance, just think of all of the weird deflections and crazy angle shots and rebounds that go in as opposed to the well executed odd man rushes, dangles and snipes from the slot. You just aren't all that likely to get the puck laying flat on your stick in a great scoring area, and at least to date, while individual players have been shown to be able to do that, its not reflected at the team level as far as shooting percentage goes. Simply put, the best way to have more chances is to have more of the puck.

As far as implementing systems that can affect possession, puck management matters. While possession is mostly driven by talent and the skills of the players, a coach can absolutely instruct the players to play in a way that will maximize possession. I'm not saying that dumping is always the wrong call, however, a team that enters the offensive zone with possession as opposed to dumping and forechecking generates more shots per offensive zone entry. This seems fairly obvious, as my mom always used to wonder before advanced hockey stats were around, "Why are you giving the puck up for a chance to get it back?" She is right that this style of play seems fairly counterproductive. That's why, whenever possible, the Soviet Union would regroup by bringing the puck back to their defensive zone and trying again when possible. They figured that even with the opposing defense already back, they could create more chances through controlled zone entries than if they played a North American style game and tried to dump and chase with numbers. There was an NHL Numbers article on that, but I'm seemingly unable to find it.

Secondly, a coach can affect these numbers in his decisions of who to play and what line combinations to use. To use an example I'm very familiar with, the Philadelphia Flyers are on a 6-0-1 run right now. with the exception of the 1st game when Michael Raffl played for an injured Steve Downie, the line combinations have been stayed the same each game. In particular, the 3rd line of Couturier, Read and Downie has been phenomenal in this stretch, shutting down strong possession lines game after game. We're talking outplaying Crosby's line, Turris's line, drawing dead even with Taveres' line in Corsi despite mostly defensive zone starts which is very impressive. By putting his best possession players in the lineup (with the exception of Jay Rosehill who plays 4th line minutes so who cares), with players that compliment their skill sets (See Giroux with Voracek, who is similar to Jaromir Jagr in that he's a big body who's strong on the puck and skilled, and with Hartnell who goes to the corners and wins puck battles, or Couturier, one of the best young defensive forwards in the NHL with a versatile two way wing and sniper like Matt Read, and a tenacious, but skilled Steve Downie) Craig Berube has a Flyers team that started the season 1-7-0 all the way to 10-10-2 and 2 points out of a playoff spot with a game in hand.

Finally, a coach can manage line matchups and zone starts in game, particularly at home when he gets the last change. Against Pittsburgh, Bylsma lost the Pens a game the probably should have won, because he allowed Berube to continually get the matchups that he wanted (Specifically Couturier against Crosby's line, and Giroux's line against Malkin's). Berube has been fantastic at getting the matchups he's wanted during this run, despite four of the seven games being on the road. He has allowed Giroux and Couturier to handle the heavy lifting in the defensive zone, because these are strong possession lines that push the play forward. He has given easier zone starts to the Schenn/Lecavalier/Simmonds line, which has scored a lot because of the decreased defensive responsibility that does not exactly fit their skill set, and increased scoring chances due to starting in a more favorable position. While Schenn might be a great two way center some day, his game is not there yet, Vinny is old, and Simmer is not the best skater. Yet when placed against weaker competition and given some favorable starting points, they are more than capable of being a good scoring line.

So in sum, yes a coach can absolutely affect possession and the run of play through the system they choose to implement, particularly regarding puck management, the lineups and line combinations they choose to play, and the matchups and zone starts they decide to give their players in game. Yes there is a fundamental limiting factor in the talent that is on the ice, but the way a coach utilizes the talent they have at hand matters.

css228

Trotsky

css228
Apologize for the long post, but I figure it was useless without some context.

Don't apologize, this is great stuff. Thank you for taking the time to write it out clearly.

I haven't followed the other links (I will), but the first thing that I wondered was is there any reason to believe puck possession is causal of success, as opposed to being simply correlated because both puck possession and success are caused by an independent variable (namely, having better players)? It does not seem like a team can simply decide they are going possess the puck more. Possession seems dependent on other things that are more in the power of the team (well, the coach) to control: recruiting for and exercising to improve strength, size, speed, conditioning, as well as some skills that are second-order effects of those things: winning the battle in the corners, beating the opponent to the puck, passing crisply, staying above the opponent.

Or are you saying that some team strategies and in-game tactics stress possession over other goods and this is disproportionately successful? Is stressing possession a disputed notion?

The major reason to believe that puck possession is causal is that it seems as though shot quality, in the sense of taking few shots but regularly creating better quality chances isn't a repeatable phenomenon. Goals are a sufficiently rare event that they are highly effected by chance, just think of all of the weird deflections and crazy angle shots and rebounds that go in as opposed to the well executed odd man rushes, dangles and snipes from the slot. You just aren't all that likely to get the puck laying flat on your stick in a great scoring area, and at least to date, while individual players have been shown to be able to do that, its not reflected at the team level as far as shooting percentage goes. Simply put, the best way to have more chances is to have more of the puck.

As far as implementing systems that can affect possession, puck management matters. While possession is mostly driven by talent and the skills of the players, a coach can absolutely instruct the players to play in a way that will maximize possession. I'm not saying that dumping is always the wrong call, however, a team that enters the offensive zone with possession as opposed to dumping and forechecking generates more shots per offensive zone entry. This seems fairly obvious, as my mom always used to wonder before advanced hockey stats were around, "Why are you giving the puck up for a chance to get it back?" She is right that this style of play seems fairly counterproductive. That's why, whenever possible, the Soviet Union would regroup by bringing the puck back to their defensive zone and trying again when possible. They figured that even with the opposing defense already back, they could create more chances through controlled zone entries than if they played a North American style game and tried to dump and chase with numbers. There was an NHL Numbers article on that, but I'm seemingly unable to find it.

Secondly, a coach can affect these numbers in his decisions of who to play and what line combinations to use. To use an example I'm very familiar with, the Philadelphia Flyers are on a 6-0-1 run right now. with the exception of the 1st game when Michael Raffl played for an injured Steve Downie, the line combinations have been stayed the same each game. In particular, the 3rd line of Couturier, Read and Downie has been phenomenal in this stretch, shutting down strong possession lines game after game. We're talking outplaying Crosby's line, Turris's line, drawing dead even with Taveres' line in Corsi despite mostly defensive zone starts which is very impressive. By putting his best possession players in the lineup (with the exception of Jay Rosehill who plays 4th line minutes so who cares), with players that compliment their skill sets (See Giroux with Voracek, who is similar to Jaromir Jagr in that he's a big body who's strong on the puck and skilled, and with Hartnell who goes to the corners and wins puck battles, or Couturier, one of the best young defensive forwards in the NHL with a versatile two way wing and sniper like Matt Read, and a tenacious, but skilled Steve Downie) Craig Berube has a Flyers team that started the season 1-7-0 all the way to 10-10-2 and 2 points out of a playoff spot with a game in hand.

Finally, a coach can manage line matchups and zone starts in game, particularly at home when he gets the last change. Against Pittsburgh, Bylsma lost the Pens a game the probably should have won, because he allowed Berube to continually get the matchups that he wanted (Specifically Couturier against Crosby's line, and Giroux's line against Malkin's). Berube has been fantastic at getting the matchups he's wanted during this run, despite four of the seven games being on the road. He has allowed Giroux and Couturier to handle the heavy lifting in the defensive zone, because these are strong possession lines that push the play forward. He has given easier zone starts to the Schenn/Lecavalier/Simmonds line, which has scored a lot because of the decreased defensive responsibility that does not exactly fit their skill set, and increased scoring chances due to starting in a more favorable position. While Schenn might be a great two way center some day, his game is not there yet, Vinny is old, and Simmer is not the best skater. Yet when placed against weaker competition and given some favorable starting points, they are more than capable of being a good scoring line.

So in sum, yes a coach can absolutely affect possession and the run of play through the system they choose to implement, particularly regarding puck management, the lineups and line combinations they choose to play, and the matchups and zone starts they decide to give their players in game. Yes there is a fundamental limiting factor in the talent that is on the ice, but the way a coach utilizes the talent they have at hand matters.

I was definitely aware of how the 3rd line was being used, but I'll watch for how Chief plays the 2nd line tonight, too. That's an interesting observation.

And as a Flyers fan, I'm loving everything you're saying. Simply because it bodes well for future games.

That is a fantastic summary, thank you. It would be great for folks (with time, and knowledge, and the willingness to work for beer...) to take a shot at evaluating the tape of the Yale game re: where we did (or did not) put these principles into practice, and whether there was anything more we could have done given who we have to work with.

In your opinion do you think Cornell takes advantage of possession-building tactics? I know we were getting outshot a zillion-to-one there for a while, but as you said in the OP that in itself doesn't mean much since 99% of those shots might have been from Barton Hall.

Jeff Hopkins '82

css228

Trotsky

css228
Apologize for the long post, but I figure it was useless without some context.

Don't apologize, this is great stuff. Thank you for taking the time to write it out clearly.

I haven't followed the other links (I will), but the first thing that I wondered was is there any reason to believe puck possession is causal of success, as opposed to being simply correlated because both puck possession and success are caused by an independent variable (namely, having better players)? It does not seem like a team can simply decide they are going possess the puck more. Possession seems dependent on other things that are more in the power of the team (well, the coach) to control: recruiting for and exercising to improve strength, size, speed, conditioning, as well as some skills that are second-order effects of those things: winning the battle in the corners, beating the opponent to the puck, passing crisply, staying above the opponent.

Or are you saying that some team strategies and in-game tactics stress possession over other goods and this is disproportionately successful? Is stressing possession a disputed notion?

The major reason to believe that puck possession is causal is that it seems as though shot quality, in the sense of taking few shots but regularly creating better quality chances isn't a repeatable phenomenon. Goals are a sufficiently rare event that they are highly effected by chance, just think of all of the weird deflections and crazy angle shots and rebounds that go in as opposed to the well executed odd man rushes, dangles and snipes from the slot. You just aren't all that likely to get the puck laying flat on your stick in a great scoring area, and at least to date, while individual players have been shown to be able to do that, its not reflected at the team level as far as shooting percentage goes. Simply put, the best way to have more chances is to have more of the puck.

As far as implementing systems that can affect possession, puck management matters. While possession is mostly driven by talent and the skills of the players, a coach can absolutely instruct the players to play in a way that will maximize possession. I'm not saying that dumping is always the wrong call, however, a team that enters the offensive zone with possession as opposed to dumping and forechecking generates more shots per offensive zone entry. This seems fairly obvious, as my mom always used to wonder before advanced hockey stats were around, "Why are you giving the puck up for a chance to get it back?" She is right that this style of play seems fairly counterproductive. That's why, whenever possible, the Soviet Union would regroup by bringing the puck back to their defensive zone and trying again when possible. They figured that even with the opposing defense already back, they could create more chances through controlled zone entries than if they played a North American style game and tried to dump and chase with numbers. There was an NHL Numbers article on that, but I'm seemingly unable to find it.

Secondly, a coach can affect these numbers in his decisions of who to play and what line combinations to use. To use an example I'm very familiar with, the Philadelphia Flyers are on a 6-0-1 run right now. with the exception of the 1st game when Michael Raffl played for an injured Steve Downie, the line combinations have been stayed the same each game. In particular, the 3rd line of Couturier, Read and Downie has been phenomenal in this stretch, shutting down strong possession lines game after game. We're talking outplaying Crosby's line, Turris's line, drawing dead even with Taveres' line in Corsi despite mostly defensive zone starts which is very impressive. By putting his best possession players in the lineup (with the exception of Jay Rosehill who plays 4th line minutes so who cares), with players that compliment their skill sets (See Giroux with Voracek, who is similar to Jaromir Jagr in that he's a big body who's strong on the puck and skilled, and with Hartnell who goes to the corners and wins puck battles, or Couturier, one of the best young defensive forwards in the NHL with a versatile two way wing and sniper like Matt Read, and a tenacious, but skilled Steve Downie) Craig Berube has a Flyers team that started the season 1-7-0 all the way to 10-10-2 and 2 points out of a playoff spot with a game in hand.

Finally, a coach can manage line matchups and zone starts in game, particularly at home when he gets the last change. Against Pittsburgh, Bylsma lost the Pens a game the probably should have won, because he allowed Berube to continually get the matchups that he wanted (Specifically Couturier against Crosby's line, and Giroux's line against Malkin's). Berube has been fantastic at getting the matchups he's wanted during this run, despite four of the seven games being on the road. He has allowed Giroux and Couturier to handle the heavy lifting in the defensive zone, because these are strong possession lines that push the play forward. He has given easier zone starts to the Schenn/Lecavalier/Simmonds line, which has scored a lot because of the decreased defensive responsibility that does not exactly fit their skill set, and increased scoring chances due to starting in a more favorable position. While Schenn might be a great two way center some day, his game is not there yet, Vinny is old, and Simmer is not the best skater. Yet when placed against weaker competition and given some favorable starting points, they are more than capable of being a good scoring line.

So in sum, yes a coach can absolutely affect possession and the run of play through the system they choose to implement, particularly regarding puck management, the lineups and line combinations they choose to play, and the matchups and zone starts they decide to give their players in game. Yes there is a fundamental limiting factor in the talent that is on the ice, but the way a coach utilizes the talent they have at hand matters.

I was definitely aware of how the 3rd line was being used, but I'll watch for how Chief plays the 2nd line tonight, too. That's an interesting observation.

And as a Flyers fan, I'm loving everything you're saying. Simply because it bodes well for future games.

There is an element of we've been playing bad teams during this run, and seven games is not nearly enough to indicate a lasting trend, but their possession numbers while losing were very bad, and in their wins with the exception of the Pittsburgh game, have been very good. Broad Street Hockey just ran an article on the improved possession today along with possible explanations. I will note I was wrong, Chief has had last change in 4 of the 7 games in this streak. He'll probably have less impact on the game tonight unless Dineen is as clueless regarding matchups as Bylsma was, given the game is in Florida.

css228

Jeff Hopkins '82

css228

Trotsky

css228
Apologize for the long post, but I figure it was useless without some context.

Don't apologize, this is great stuff. Thank you for taking the time to write it out clearly.

I haven't followed the other links (I will), but the first thing that I wondered was is there any reason to believe puck possession is causal of success, as opposed to being simply correlated because both puck possession and success are caused by an independent variable (namely, having better players)? It does not seem like a team can simply decide they are going possess the puck more. Possession seems dependent on other things that are more in the power of the team (well, the coach) to control: recruiting for and exercising to improve strength, size, speed, conditioning, as well as some skills that are second-order effects of those things: winning the battle in the corners, beating the opponent to the puck, passing crisply, staying above the opponent.

Or are you saying that some team strategies and in-game tactics stress possession over other goods and this is disproportionately successful? Is stressing possession a disputed notion?

The major reason to believe that puck possession is causal is that it seems as though shot quality, in the sense of taking few shots but regularly creating better quality chances isn't a repeatable phenomenon. Goals are a sufficiently rare event that they are highly effected by chance, just think of all of the weird deflections and crazy angle shots and rebounds that go in as opposed to the well executed odd man rushes, dangles and snipes from the slot. You just aren't all that likely to get the puck laying flat on your stick in a great scoring area, and at least to date, while individual players have been shown to be able to do that, its not reflected at the team level as far as shooting percentage goes. Simply put, the best way to have more chances is to have more of the puck.

As far as implementing systems that can affect possession, puck management matters. While possession is mostly driven by talent and the skills of the players, a coach can absolutely instruct the players to play in a way that will maximize possession. I'm not saying that dumping is always the wrong call, however, a team that enters the offensive zone with possession as opposed to dumping and forechecking generates more shots per offensive zone entry. This seems fairly obvious, as my mom always used to wonder before advanced hockey stats were around, "Why are you giving the puck up for a chance to get it back?" She is right that this style of play seems fairly counterproductive. That's why, whenever possible, the Soviet Union would regroup by bringing the puck back to their defensive zone and trying again when possible. They figured that even with the opposing defense already back, they could create more chances through controlled zone entries than if they played a North American style game and tried to dump and chase with numbers. There was an NHL Numbers article on that, but I'm seemingly unable to find it.

Secondly, a coach can affect these numbers in his decisions of who to play and what line combinations to use. To use an example I'm very familiar with, the Philadelphia Flyers are on a 6-0-1 run right now. with the exception of the 1st game when Michael Raffl played for an injured Steve Downie, the line combinations have been stayed the same each game. In particular, the 3rd line of Couturier, Read and Downie has been phenomenal in this stretch, shutting down strong possession lines game after game. We're talking outplaying Crosby's line, Turris's line, drawing dead even with Taveres' line in Corsi despite mostly defensive zone starts which is very impressive. By putting his best possession players in the lineup (with the exception of Jay Rosehill who plays 4th line minutes so who cares), with players that compliment their skill sets (See Giroux with Voracek, who is similar to Jaromir Jagr in that he's a big body who's strong on the puck and skilled, and with Hartnell who goes to the corners and wins puck battles, or Couturier, one of the best young defensive forwards in the NHL with a versatile two way wing and sniper like Matt Read, and a tenacious, but skilled Steve Downie) Craig Berube has a Flyers team that started the season 1-7-0 all the way to 10-10-2 and 2 points out of a playoff spot with a game in hand.

Finally, a coach can manage line matchups and zone starts in game, particularly at home when he gets the last change. Against Pittsburgh, Bylsma lost the Pens a game the probably should have won, because he allowed Berube to continually get the matchups that he wanted (Specifically Couturier against Crosby's line, and Giroux's line against Malkin's). Berube has been fantastic at getting the matchups he's wanted during this run, despite four of the seven games being on the road. He has allowed Giroux and Couturier to handle the heavy lifting in the defensive zone, because these are strong possession lines that push the play forward. He has given easier zone starts to the Schenn/Lecavalier/Simmonds line, which has scored a lot because of the decreased defensive responsibility that does not exactly fit their skill set, and increased scoring chances due to starting in a more favorable position. While Schenn might be a great two way center some day, his game is not there yet, Vinny is old, and Simmer is not the best skater. Yet when placed against weaker competition and given some favorable starting points, they are more than capable of being a good scoring line.

So in sum, yes a coach can absolutely affect possession and the run of play through the system they choose to implement, particularly regarding puck management, the lineups and line combinations they choose to play, and the matchups and zone starts they decide to give their players in game. Yes there is a fundamental limiting factor in the talent that is on the ice, but the way a coach utilizes the talent they have at hand matters.

I was definitely aware of how the 3rd line was being used, but I'll watch for how Chief plays the 2nd line tonight, too. That's an interesting observation.

And as a Flyers fan, I'm loving everything you're saying. Simply because it bodes well for future games.

There is an element of we've been playing bad teams during this run, and seven games is not nearly enough to indicate a lasting trend, but their possession numbers while losing were very bad, and in their wins with the exception of the Pittsburgh game, have been very good. Broad Street Hockey just ran an article on the improved possession today along with possible explanations. I will note I was wrong, Chief has had last change in 4 of the 7 games in this streak. He'll probably have less impact on the game tonight unless Dineen is as clueless regarding matchups as Bylsma was, given the game is in Florida.

Up until recently those teams still had a better record than the Flyers, so I'll take what solace I can get. And let's face it, Florida is not exactly a hockey power.

But you're right, there will be some tougher games coming up in the upcoming road trips, and we'll see more of how it plays out.

Trotsky
That is a fantastic summary, thank you. It would be great for folks (with time, and knowledge, and the willingness to work for beer...) to take a shot at evaluating the tape of the Yale game re: where we did (or did not) put these principles into practice, and whether there was anything more we could have done given who we have to work with.

In your opinion do you think Cornell takes advantage of possession-building tactics? I know we were getting outshot a zillion-to-one there for a while, but as you said in the OP that in itself doesn't mean much since 99% of those shots might have been from Barton Hall.

I think we dump and chase far more often than we have to, but at the same time, some of that might be accounted for by who is on the puck at any given time. I'd much rather Cole Bardreau or Brian Ferlin take a risk and try to beat a defender to carry in than Armand De Swardt. Some players are just better in the neutral zone than others. Guys who probably should be trying to make plays, because their skill set really is more offense oriented include Ferlin, Bardreau, Lowry, Gotovets, Willcox, Ryan, and maybe even Mowery. This doesn't mean there aren't situations where they should still dump or shoot in. I think it'd be interesting to see what would happen if Cornell attempted to regroup a la the Soviet Union instead of dumping sometime, but as a college team, I'm not sure the talent level of our players is high enough for that strategy to work as well for us as it did for one of the greatest hockey teams of all time.

Regarding player usage, I do not see a consistent pattern of player usage when I'm at games, but I'll admit, it's hard to focus on that from Section B.And really the person who knows how to best utilize the players is the guy who sees them at practice every day. I'd argue Bardreau is very good at pushing the play forward and his line is good at winning puck battles, and therefore you might want to use them with some tougher zone starts, freeing up the Ferlin line to have more offensive zone starts. But that raises the question should Bardreau's line be matching up with the opponent's top line every game? It is very difficult to score against top competition unless you are the elitest of the elite (Think Datsyuk, Zetterberg, and whatever player is lucky enough to have those two carry him to greatness). So maybe you play Bardreau against the 2nd best line that an opponent has to offer if you think you have the players to create a dedicated shut down line on the third line. I personally believe Bardreau's line is our best line in both directions, and therefore should be taking on the toughest competition we face, but it's really not my call to make.

But that said, in recruiting, the coaches really should focus on neutral zone play. It really does seem to be the most important zone in hockey.

css228
There was an NHL Numbers article on that, but I'm seemingly unable to find it.

I believe these are the articles you had in mind:

A Season's Worth of Zone Entries

More on the Advantages of Puck Possession

I'm still not convinced that confounding factors don't explain much of the apparent advantages of carrying the puck into the zone. I would love to see future studies on this, however. I suspect defensive positioning is the biggest factor affecting the decision to carry or dump. I wonder whether regrouping would provide real advantages, if a team without the puck has three or four guys in good positioning near its blue line and can retain that advantageous defensive positioning if the puck carrying team regroups.

This is a great thread. It's so wonderful to have such knowledgeable posters.

I have two questions:

1. What about line changes? Dumping is often used to allow line changes, so a team that changes more frequently dumps more often. How does this fit into the analysis.
2. Doesn't puck control require schemes for getting through neutral ice? In turn, this requires practice, and a coach can greatly influence how a team breaks out and makes its way through the neutral zone.

BTW, when I coached youth soccer I read many books on the subject. Many (all?) of the better ones stressed getting players to shoot rather than wait for a perfect situation.
Also BTW, at least in college hockey, part of puck possession depends on speed, strength, etc., which are by no means evenly distributed between teams. So some of the correlation may be an artifact of talent rather than strategy.

Makes me ponder if there would be any interesting information that could be gleaned from creating a metric for each individual player of "probability that the player will NOT turn the puck over." It's a bit like the Moneyball philosophy - the probability of NOT getting an out. Since the idea seems to be that possessing the puck for longer stretches leads to goals (or perhaps even better - leads to a higher favorable goal differential), then what you want on your team is a bunch of players who do not turn the puck over. It shouldn't matter whether this is because they can all stickhandle like Guy LaFluer and can curl back into our own zone to maintain possession or if they dump and chase all the time but are so fast and strong that they usually come away with the puck anyway. Either way, they didn't turn the puck over, and therefore have a higher chance of scoring the next goal. So the stat would be something like, "once player X has possession of the puck, what is the percentage of the time that the next player who possesses the puck is on the opposite team?" Obviously, scoring a goal is not a possession by the other team, so you'd get credit for that, too.

Swampy
This is a great thread. It's so wonderful to have such knowledgeable posters.

I have two questions:

1. What about line changes? Dumping is often used to allow line changes, so a team that changes more frequently dumps more often. How does this fit into the analysis.
2. Doesn't puck control require schemes for getting through neutral ice? In turn, this requires practice, and a coach can greatly influence how a team breaks out and makes its way through the neutral zone.

BTW, when I coached youth soccer I read many books on the subject. Many (all?) of the better ones stressed getting players to shoot rather than wait for a perfect situation.
Also BTW, at least in college hockey, part of puck possession depends on speed, strength, etc., which are by no means evenly distributed between teams. So some of the correlation may be an artifact of talent rather than strategy.

Regarding question A, there are absolutely times when dumping is the right call, line changes being one of them. I don't think there is any hockey mind that would argue differently. Regarding question B, controlling the neutral zone is not only an offensive matter it is a defensive matter. Playing strong defense and denying the blue line is every bit as important as entering the offensive zone with controlled entries. There isn't only one type of team that is successful. You can win with elite offense, elite defense, or even both. The clutch and grab era Devils weren't great because they were an offensive juggernaut, but because they were impossible to enter the offensive zone against with possession, partially due to the rules of the game at the time.Finally, being a good puck possession team is absolutely about talent first and foremost. Talented teams possess the puck, and talented teams win. But if a coach is telling his third line to dump and forecheck in most situations, they may be giving up shots when taking a little more risk might bring more rewards. Finally, puck possession skills are not always the most apparent, because they do not show up in the traditional stats. A player with a 58% CorsiFor may not sound as sexy as a 40 goal scorer, but that means that these players are often undervalued. Look at all the idiots in Philadelphia who want Sean Couturier traded because he isn't scoring. Who cares if he's scoring when he's a 20 year old 3rd line center who consistently drives play to the offensive end despite tough zone starts and competition? If he continues to do that, the points will come, but in the meantime, he's massively undervalued. If coaches look for players with skill sets that drive play into the offensive zone, they may be able to get players other coaches have overlooked, but will win them hockey games. Coaching is about putting players in positions to succeed, and utilizing the talent you have most efficiently. Strategy might be 10% of the game maximum, but in a game with as much random chance as hockey, I'll take every little bit of extra advantage I can get.

Robb
Makes me ponder if there would be any interesting information that could be gleaned from creating a metric for each individual player of "probability that the player will NOT turn the puck over." It's a bit like the Moneyball philosophy - the probability of NOT getting an out. Since the idea seems to be that possessing the puck for longer stretches leads to goals (or perhaps even better - leads to a higher favorable goal differential), then what you want on your team is a bunch of players who do not turn the puck over. It shouldn't matter whether this is because they can all stickhandle like Guy LaFluer and can curl back into our own zone to maintain possession or if they dump and chase all the time but are so fast and strong that they usually come away with the puck anyway. Either way, they didn't turn the puck over, and therefore have a higher chance of scoring the next goal. So the stat would be something like, "once player X has possession of the puck, what is the percentage of the time that the next player who possesses the puck is on the opposite team?" Obviously, scoring a goal is not a possession by the other team, so you'd get credit for that, too.

The way the guys at Broad Street Hockey have been focusing on it is through defensive zone exits and offensive zone entries. Specifically on the zone exits, they've looked at how successful players are in their attempts to take the puck out of the zone, and what percentage of their successful exits are with possession. Then in the neutral zone they have looked at zone entries to the offensive zone, in a similar fashion. They want to know how many entries were successful, and of those, what percentage occurred with possession, because at least with the Flyers and the Wild, they came across an interesting finding. "Skilled offensive players" did not appreciably have more success in shots per carry in/pass or shots per dump in/deflect in than "unskilled players". In fact Claude Giroux, who had 93 points in the 2011-2012 season which they did this for, averaged as many shots per carry in/pass (.52) as Maxime Talbot, and fewer than Zac Rinaldo (.56). The big difference was that Giroux entered the offensive zone with possession of the puck on 67% of his successful entries and played on a line with Jagr (74% entries with possession) and Hartnell (56% entries with possession), while Talbot was at 43% playing with Rinaldo (49%) and Couturier (at the time 18 years old and at 45%). The difference in skill was apparent not in the offensive zone, but in the neutral zone. Giroux won the neutral zone more often, in a more productive manner.

This is not to say that if Rinaldo or Talbot started to carry in the puck more they would become Giroux. But it does suggest, that instead of being encouraged and coached to be an energy line that dumps and forechecks, that they should try to take the zone with possession when possible. If not they're just giving away scoring chances. Finally regarding giveaways, I'm not sure this is the best thing to look at, because a lot of players who push the puck forward have a lot of giveaways. Matt Carle comes to mind, and I'm sure P.K. Subban fits the role too. A Cornell comparison might be Gotovets. Yes he takes greater risks to carry the puck in a lot of situations, but those infuriating turnovers can be offset because if he is successful enough carrying the puck in, he is creating shots at about twice the rate he would be by dumping and chasing. There is an element of this to Subban's game, which is why Canada may, regretfully, pass over him for the Olympics. Isles and Flyers fans probably see the same thing in Mark Streit. Some of the games best puck movers and elite offensive players see more turnovers, but those turnovers are outweighed by the positions they put other players in when the risks they take do succeed. There is more than one way to be an above average, or even elite possession player. Hartnell and Giroux's skill sets have almost nothing in common, but they're both very good at driving play in the right direction. It's not that turnovers don't matter, its just that I'm not sure they're the right way to value possession because it really only covers one aspect of how possession is maintained. If that's not what you are referring to, then let me know. I think of all sports hockey is a very difficult one to really maintain possession in a traditional sense and its very hard to quantify what makes a player a good possession player beyond, when he's on the ice, we get more of the shots.

I think we might be using the term "turnover" differently. To me, any time you have the puck, it leaves your stick, and a player from the other team gains control, that's a turnover. It doesn't matter if it's because you tried to carry the puck in, or because you were standing still and made a lousy pass, or because you are a great passer who made a risky pass, or because you carried it to the end wall and were muscled off the puck. You had it, now the other team does = turnover. I have to think you'd have a pretty good hockey team if you could pick and choose the players who turn it over the least (based on "my" definition above).

Robb
I think we might be using the term "turnover" differently. To me, any time you have the puck, it leaves your stick, and a player from the other team gains control, that's a turnover. It doesn't matter if it's because you tried to carry the puck in, or because you were standing still and made a lousy pass, or because you are a great passer who made a risky pass, or because you carried it to the end wall and were muscled off the puck. You had it, now the other team does = turnover. I have to think you'd have a pretty good hockey team if you could pick and choose the players who turn it over the least (based on "my" definition above).

Yeah, I'm using turnover in the sense of giveaways as they record in the statistics. By your standard, would a shot that ended up in the other team possessing the puck count as a turnover? That seems like a productive use of the puck. Furthermore, What if you get muscled off the puck, but win it back with a good forecheck? What I'm trying to say is that it seems most important to focus on what is occurring in the neutral zone in terms of denying the blue line with possession on defense and gaining it with possession on offense. Let's face it, even if you gain the zone and win possession with a dump, you've won it most likely behind the goal or in a corner, which is a far less threatening position than possession of the puck headed in the direction of the net. Puck possession will change in the offensive and defensive zones just because of the limitations on space that is usable for the offensive team. It seems more critical to me at least to maintain possession when the entire ice surface is at your disposal, and that maintaining offensive zone time, while important, is not as critical as pushing it in the direction of the offensive zone the majority of the time when the puck is in the neutral zone. I'm still not sure this is what you're getting at, but I hope its closer.

This article posted today on puckpossession.com suggests that the strength of Fenwick Close's predictive value has been overestimated by the analytics community. As a bonus, the post contains a photo of Douglas Murray and others doing a stick salute after a Sharks' game on home ice a couple of years ago.

css228
Yeah, I'm using turnover in the sense of giveaways as they record in the statistics. By your standard, would a shot that ended up in the other team possessing the puck count as a turnover? That seems like a productive use of the puck.

Not necessarily. Would you really be happy as a coach if one of your players consistently put the puck on net with wrist shots from outside the blue line? Of course not - because it's a turnover. On the other hand, if you have a player who consistently puts the puck on the net where there's a good chance for a rebound, then that's different - because there's an opportunity for it NOT to be a turnover (a pad or blocker save is not a turnover in my accounting method - it depends who picks up the rebound).

css228
Furthermore, What if you get muscled off the puck, but win it back with a good forecheck?

"Winning it back" is probably a separate skill that is also important that would not show up in my metric.

css228
What I'm trying to say is that it seems most important to focus on what is occurring in the neutral zone in terms of denying the blue line with possession on defense and gaining it with possession on offense. Let's face it, even if you gain the zone and win possession with a dump, you've won it most likely behind the goal or in a corner, which is a far less threatening position than possession of the puck headed in the direction of the net. Puck possession will change in the offensive and defensive zones just because of the limitations on space that is usable for the offensive team. It seems more critical to me at least to maintain possession when the entire ice surface is at your disposal, and that maintaining offensive zone time, while important, is not as critical as pushing it in the direction of the offensive zone the majority of the time when the puck is in the neutral zone. I'm still not sure this is what you're getting at, but I hope its closer.

Maybe, but I still feel like you're "overthinking" it a little - you're trying to break it down by what type of possession is most important, etc. I prefer to underthink, or better yet, not think at all. To me, possession = good, losing puck = bad. Doesn't matter whether you're maintaining possession in your own zone (limits oppponent's chances), the neutral zone (better opportunities for carrying into the zone), or in the attacking zone (keeps opportunity for generating a shot alive). Why bother trying to decide ahead of time which is most important? Just lump them all together - a player who is good at maintaining posession in any of the three zones is welcome on "my" team.

I'm not saying my method is better - I certainly don't have the data or the time to actually do any studies. Heck, for all I know, the data could show that losing teams are made up of lots of guys who *overvalue* puck possession and therefore never take shots and therefore never score. Just idle speculation on my part and wondering IF such a simple metric could be at all informative or useful.

cbuckser
This article posted today on puckpossession.com suggests that the strength of Fenwick Close's predictive value has been overestimated by the analytics community. As a bonus, the post contains a photo of Douglas Murray and others doing a stick salute after a Sharks' game on home ice a couple of years ago.

Interesting. Always good to question the assumptions and conclusions that have been drawn in an effort to come to better stronger conclusions. I definitely want to see how this type of analysis would play over a longer period than a quarter NHL season.

Robb

css228
Yeah, I'm using turnover in the sense of giveaways as they record in the statistics. By your standard, would a shot that ended up in the other team possessing the puck count as a turnover? That seems like a productive use of the puck.

Not necessarily. Would you really be happy as a coach if one of your players consistently put the puck on net with wrist shots from outside the blue line? Of course not - because it's a turnover. On the other hand, if you have a player who consistently puts the puck on the net where there's a good chance for a rebound, then that's different - because there's an opportunity for it NOT to be a turnover (a pad or blocker save is not a turnover in my accounting method - it depends who picks up the rebound).

css228
Furthermore, What if you get muscled off the puck, but win it back with a good forecheck?

"Winning it back" is probably a separate skill that is also important that would not show up in my metric.

css228
What I'm trying to say is that it seems most important to focus on what is occurring in the neutral zone in terms of denying the blue line with possession on defense and gaining it with possession on offense. Let's face it, even if you gain the zone and win possession with a dump, you've won it most likely behind the goal or in a corner, which is a far less threatening position than possession of the puck headed in the direction of the net. Puck possession will change in the offensive and defensive zones just because of the limitations on space that is usable for the offensive team. It seems more critical to me at least to maintain possession when the entire ice surface is at your disposal, and that maintaining offensive zone time, while important, is not as critical as pushing it in the direction of the offensive zone the majority of the time when the puck is in the neutral zone. I'm still not sure this is what you're getting at, but I hope its closer.

Maybe, but I still feel like you're "overthinking" it a little - you're trying to break it down by what type of possession is most important, etc. I prefer to underthink, or better yet, not think at all. To me, possession = good, losing puck = bad. Doesn't matter whether you're maintaining possession in your own zone (limits oppponent's chances), the neutral zone (better opportunities for carrying into the zone), or in the attacking zone (keeps opportunity for generating a shot alive). Why bother trying to decide ahead of time which is most important? Just lump them all together - a player who is good at maintaining posession in any of the three zones is welcome on "my" team.

I'm not saying my method is better - I certainly don't have the data or the time to actually do any studies. Heck, for all I know, the data could show that losing teams are made up of lots of guys who *overvalue* puck possession and therefore never take shots and therefore never score. Just idle speculation on my part and wondering IF such a simple metric could be at all informative or useful.

The thing is that shots attempts, and shot attempts - blocked shots are the best proxies we have for possession. So good in fact that it's a waste of time to take a stopwatch and time zone time. Possession in hockey is defined by whether or not the majority of shots go for your team when a given player is on the ice. So I don't think possession in the way the analytics community measures it is something that can be overvalued by the player. If they valued possession so highly that they never shot, then they probably wouldn't rate very well on the metrics that are currently used for possession. Just some thoughts

Oh my - so "happy" to have stumbled upon this .....

I have major problems with the advanced hockey metrics folks. Not as people, of course, but their conclusions.

I believe at least 50% of this stuff is bunk - in the sense that the conclusions reached are flawed, and the people making the conclusions make them much too definitively.

Corsi is a useful indicator if taken with a grain of salt. But it has so many holes in the logic.

Anecdotally, Cornell, a team that possesses the puck a lot but doesn't get an inordinate amount of shots, should be a prime example of the flaws. Also, since the last thing you want is a team to take shots from anywhere on the ice, just to improve their Corsi, then what use is there in the numbers. That is why it's not necessarily a causal relationship. And what might correlate on a very macro level, doesn't necessarily translate into anything useful on a game-to-game basis.

Note this ... penalty minutes also correlates (inversely) to winning in exactly the same measure as Corsi. Yet I don't see anyone breaking down PIMs per game as some sort of end all be all. If so, Matt Moulson would be best player in the NHL.

And I say this as someone who thinks Bill James is a god - though I don't have any data to back that up.

I think of all sports hockey is a very difficult one to really maintain possession in a traditional sense and its very hard to quantify what makes a player a good possession player beyond, when he's on the ice, we get more of the shots.

And herein lies one of the biggest problems with drawing conclusions based on shot totals.

cbuckser
This article posted today on puckpossession.com suggests that the strength of Fenwick Close's predictive value has been overestimated by the analytics community. As a bonus, the post contains a photo of Douglas Murray and others doing a stick salute after a Sharks' game on home ice a couple of years ago.

May god bless you for posting this.

adamw
Oh my - so "happy" to have stumbled upon this .....

I have major problems with the advanced hockey metrics folks. Not as people, of course, but their conclusions.

I believe at least 50% of this stuff is bunk - in the sense that the conclusions reached are flawed, and the people making the conclusions make them much too definitively.

Corsi is a useful indicator if taken with a grain of salt. But it has so many holes in the logic.

Anecdotally, Cornell, a team that possesses the puck a lot but doesn't get an inordinate amount of shots, should be a prime example of the flaws. Also, since the last thing you want is a team to take shots from anywhere on the ice, just to improve their Corsi, then what use is there in the numbers. That is why it's not necessarily a causal relationship. And what might correlate on a very macro level, doesn't necessarily translate into anything useful on a game-to-game basis.

Note this ... penalty minutes also correlates (inversely) to winning in exactly the same measure as Corsi. Yet I don't see anyone breaking down PIMs per game as some sort of end all be all. If so, Matt Moulson would be best player in the NHL.

And I say this as someone who thinks Bill James is a god - though I don't have any data to back that up.

The counterpoint to your anecdote is that Cornell's most successful seasons under Schafer were ones in which they outshot their opponents pretty heavily.

The article about Fenwick Close says exactly what I'd expect for a metric of that type - a better Fenwick close indicates a somewhat larger probability of winning, and over a season that translates into more points, but it's not useful for single game or even playoff series prediction. That's not surprising - it's like saying you can use OPS to determine which players are the best hitters, but you can't reliably predict which player will have the best game, or even the best series. The sample sizes are just too small relative to the variance in outcomes.

I haven't looked into hockey analytics closely, and I get the sense that they're still in the early stages (particularly compared to baseball), but I'm always cautious about dismissing simple metrics out of hand because they miss things that seem obvious. Just as OPS is a simple yet powerful indicator of a hitter's strength relative to competition, I wouldn't be surprised if normalized shot differentials were similarly powerful as indicators of a team's strength. It makes intuitive sense, too - Cornell is going to win more often with 20-11 shot differentials than 20-35, and given a long season will probably win more often when outshooting opponents 20-11 than when outshooting opponents 30-28. Sure, there is context there that matters, but most of the context that matters is kind of preposterous when extended out over 20-30 games (e.g., Cornell is always dumping in on net while the opposition is always getting open looks on the back post).

Anyway, I'll be interested to learn more about this stuff when I get the time. In particular, I wonder about the quick dismissal of shot quality as a factor. I'm willing to believe that an *offense* can't reliably control shot quality due to the large component of chance involved, but I have to wonder about a *defense* - if a team is slightly overmatched on possession through the neutral zone, can it consistently overcome that disadvantage with defensive zone play that minimizes shot quality? Does anyone know of a study of this?

Tom Lento

adamw
Oh my - so "happy" to have stumbled upon this .....

I have major problems with the advanced hockey metrics folks. Not as people, of course, but their conclusions.

I believe at least 50% of this stuff is bunk - in the sense that the conclusions reached are flawed, and the people making the conclusions make them much too definitively.

Corsi is a useful indicator if taken with a grain of salt. But it has so many holes in the logic.

Anecdotally, Cornell, a team that possesses the puck a lot but doesn't get an inordinate amount of shots, should be a prime example of the flaws. Also, since the last thing you want is a team to take shots from anywhere on the ice, just to improve their Corsi, then what use is there in the numbers. That is why it's not necessarily a causal relationship. And what might correlate on a very macro level, doesn't necessarily translate into anything useful on a game-to-game basis.

Note this ... penalty minutes also correlates (inversely) to winning in exactly the same measure as Corsi. Yet I don't see anyone breaking down PIMs per game as some sort of end all be all. If so, Matt Moulson would be best player in the NHL.

And I say this as someone who thinks Bill James is a god - though I don't have any data to back that up.

The counterpoint to your anecdote is that Cornell's most successful seasons under Schafer were ones in which they outshot their opponents pretty heavily.

The article about Fenwick Close says exactly what I'd expect for a metric of that type - a better Fenwick close indicates a somewhat larger probability of winning, and over a season that translates into more points, but it's not useful for single game or even playoff series prediction. That's not surprising - it's like saying you can use OPS to determine which players are the best hitters, but you can't reliably predict which player will have the best game, or even the best series. The sample sizes are just too small relative to the variance in outcomes.

I haven't looked into hockey analytics closely, and I get the sense that they're still in the early stages (particularly compared to baseball), but I'm always cautious about dismissing simple metrics out of hand because they miss things that seem obvious. Just as OPS is a simple yet powerful indicator of a hitter's strength relative to competition, I wouldn't be surprised if normalized shot differentials were similarly powerful as indicators of a team's strength. It makes intuitive sense, too - Cornell is going to win more often with 20-11 shot differentials than 20-35, and given a long season will probably win more often when outshooting opponents 20-11 than when outshooting opponents 30-28. Sure, there is context there that matters, but most of the context that matters is kind of preposterous when extended out over 20-30 games (e.g., Cornell is always dumping in on net while the opposition is always getting open looks on the back post).

Anyway, I'll be interested to learn more about this stuff when I get the time. In particular, I wonder about the quick dismissal of shot quality as a factor. I'm willing to believe that an *offense* can't reliably control shot quality due to the large component of chance involved, but I have to wonder about a *defense* - if a team is slightly overmatched on possession through the neutral zone, can it consistently overcome that disadvantage with defensive zone play that minimizes shot quality? Does anyone know of a study of this?

The defense aspect is why people consider Fenwick a better indicator than Corsi. Fenwick is Shot Attempts - Blocked Shots, because it considers shot blocking a repeatable skill instead of an event driven by chance. Basically, having a good Corsi or Fenwick can be caused in two ways, either you're really elite defensively, and deny offensive zone entries and shots, or you create a lot of chances on the offensive end. It is entirely possible for a team to take only 40 shot attempts a game and still have 50% + Corsi for if they're playing good 5 v. 5 defense. It's not necessarily that shooting more is important as much as having the majority of shooting attempts. The idea is that possession matters, and that having more shot attempts is an indication that you have more possession. It's really about a process rather than anything else. Over time, good process wins games more often than not. This is why the Kings and the Blackhawks have been elite for the last few years. They're far and away the two best possession hockey teams in the NHL. Meanwhile, the Leafs who are the champions of the hockey analytics skeptics, don't look so hot right now, because they're not longer getting goaltending at a historically good level. I've said this multiple times, this is something that tends to work out over the long run, and I've made no claims that this should be used to predict game to game because any game is susceptible to small sample size variance. Just this weekend the Flyers were heavily outplayed by the Preds (or Perds if you listen to their twitter), but won in a shootout anyway because Steve Mason (Yeah who would have thought anyone would ever say that. Really hoping that's not small sample size). But Mason isn't going to be that good every game, and more often than not if a team gets that badly outplayed, they lose. Cornell has mostly been outplayed this season, and we've been lucky to win a lot despite being outplayed. Last Saturday, we dominated an inferior team, and lost. The results ultimately matter more than the process, but a process like saturday's game will ultimately win us a lot more games going forward than a process like we've seen most of the season.

Tom Lento
I haven't looked into hockey analytics closely, and I get the sense that they're still in the early stages (particularly compared to baseball), but I'm always cautious about dismissing simple metrics out of hand because they miss things that seem obvious. Just as OPS is a simple yet powerful indicator of a hitter's strength relative to competition, I wouldn't be surprised if normalized shot differentials were similarly powerful as indicators of a team's strength. It makes intuitive sense, too - Cornell is going to win more often with 20-11 shot differentials than 20-35, and given a long season will probably win more often when outshooting opponents 20-11 than when outshooting opponents 30-28. Sure, there is context there that matters, but most of the context that matters is kind of preposterous when extended out over 20-30 games (e.g., Cornell is always dumping in on net while the opposition is always getting open looks on the back post).

Anyway, I'll be interested to learn more about this stuff when I get the time. In particular, I wonder about the quick dismissal of shot quality as a factor. I'm willing to believe that an *offense* can't reliably control shot quality due to the large component of chance involved, but I have to wonder about a *defense* - if a team is slightly overmatched on possession through the neutral zone, can it consistently overcome that disadvantage with defensive zone play that minimizes shot quality? Does anyone know of a study of this?

Suggesting that shot quality doesn't matter would be folly - so even if it can't be measured properly yet, it has to be a factor.

Certainly, more shots, you would think, would be better than having less shots. No one argues that. The problem is, way too much context is lost, and is too hard to measure - making this stuff, for the time being, not very informative. My issue is when people use these metrics to make absolute determinations on a players' worth, based upon the metric alone. Just because the metric correlates well on a macro level, doesn't necessarily mean it's useful on a player level.

Your OPS example makes sense, on one hand. However, I believe the hockey metrics people are trying too hard to say "look, we've solved hockey just like baseball was solved before." There way too many other factors.

Here is the main difference between OPS and Corsi. OPS is a direct building block to scoring runs. You would never tell a baseball player "get on base less" or "please hit home runs only to this spot, or at this time". Whereas with shots ... you can't say that the solution to improving your game is simply shooting the puck more. That may or may not be the case, but you can't know that.

You could improve your Corsi by taking 50 shots from center ice. That doesn't make it a good idea. So that's the enormous difference between something like OPS and Corsi.

The Corsi people will tell you that it's insignificant -- but it's only insignificant because hockey players are all pretty good at the NHL level, and because they don't just randomly shoot from anywhere to improve their Corsi.

My point is, if a statistic is that open to flaws, is it really that useful? The metrics people need to dig deeper to find something that really, truly correlates to, and is the cause of, winning hockey games.

css228
This is why the Kings and the Blackhawks have been elite for the last few years. They're far and away the two best possession hockey teams in the NHL. Meanwhile, the Leafs who are the champions of the hockey analytics skeptics, don't look so hot right now, because they're not longer getting goaltending at a historically good level.

Or, perhaps it's because the Leafs are missing their top 3 centers during this stretch. Maybe?

And perhaps the Kings and Blackhawks are the top possession teams because they're elite - not the other way around. They're not the same thing. You may say the distinction is irrelevant - but my point, we don't know which is the cause and which is the effect. This makes it less than useful in truly explaining anything.

In baseball, I can definitively say - a team that gets on base and hits a lot of home runs, is going to be really, really good - because they're doing that. We can't say that definitively in hockey, other than to say that, if you have the puck a lot, intuitively you'd think that would be more helpful.

adamw

Tom Lento
I haven't looked into hockey analytics closely, and I get the sense that they're still in the early stages (particularly compared to baseball), but I'm always cautious about dismissing simple metrics out of hand because they miss things that seem obvious. Just as OPS is a simple yet powerful indicator of a hitter's strength relative to competition, I wouldn't be surprised if normalized shot differentials were similarly powerful as indicators of a team's strength. It makes intuitive sense, too - Cornell is going to win more often with 20-11 shot differentials than 20-35, and given a long season will probably win more often when outshooting opponents 20-11 than when outshooting opponents 30-28. Sure, there is context there that matters, but most of the context that matters is kind of preposterous when extended out over 20-30 games (e.g., Cornell is always dumping in on net while the opposition is always getting open looks on the back post).

Anyway, I'll be interested to learn more about this stuff when I get the time. In particular, I wonder about the quick dismissal of shot quality as a factor. I'm willing to believe that an *offense* can't reliably control shot quality due to the large component of chance involved, but I have to wonder about a *defense* - if a team is slightly overmatched on possession through the neutral zone, can it consistently overcome that disadvantage with defensive zone play that minimizes shot quality? Does anyone know of a study of this?

Suggesting that shot quality doesn't matter would be folly - so even if it can't be measured properly yet, it has to be a factor.

Certainly, more shots, you would think, would be better than having less shots. No one argues that. The problem is, way too much context is lost, and is too hard to measure - making this stuff, for the time being, not very informative. My issue is when people use these metrics to make absolute determinations on a players' worth, based upon the metric alone. Just because the metric correlates well on a macro level, doesn't necessarily mean it's useful on a player level.

Your OPS example makes sense, on one hand. However, I believe the hockey metrics people are trying too hard to say "look, we've solved hockey just like baseball was solved before." There way too many other factors.

Here is the main difference between OPS and Corsi. OPS is a direct building block to scoring runs. You would never tell a baseball player "get on base less" or "please hit home runs only to this spot, or at this time". Whereas with shots ... you can't say that the solution to improving your game is simply shooting the puck more. That may or may not be the case, but you can't know that.

You could improve your Corsi by taking 50 shots from center ice. That doesn't make it a good idea. So that's the enormous difference between something like OPS and Corsi.

The Corsi people will tell you that it's insignificant -- but it's only insignificant because hockey players are all pretty good at the NHL level, and because they don't just randomly shoot from anywhere to improve their Corsi.

My point is, if a statistic is that open to flaws, is it really that useful? The metrics people need to dig deeper to find something that really, truly correlates to, and is the cause of, winning hockey games.

But you can also improve your Corsi by winning puck battles on boards, making good first passes out of the defensive zone, and denying clean zone entries by opponents. Yeah you could throw the puck on net at anytime anywhere, but bad shots tend to turn into opportunities the other way and one and done possessions that over the long term wouldn't show up well in possession metrics.

Yes hockey analytics have a way to go, and are probably underdeveloped at this point, but they look like they're on to something, and these metrics will improve over time. Skepticism is a good thing because it forces people to ask if there is a better measure out there. But outrightly dismissing these numbers as useless seems mistaken to me. You keep harping on the fact that the solution of the game is not to simply shoot more. I agree, and have said multiple times that it is not about shooting more as opposed to controlling the majority of the shot attempts. You could theoretically shoot less than before, but if you became more effective defensively at denying clean zone entries and shot opportunities, come out ahead in puck possession.

No one measure is meant to be the be all and end all of value, that is why there are multiple varieties of Corsi and Fenwick that account for the strength of teammates and the quality of competition faced. That's why we look at PDO to see who might be getting lucky or unlucky. In baseball, there are disagreements by the metrics people over what matters. That's why there are 3 types of defensive independent pitching statistics (FIP, xFIP, and SIERA). Even WAR is not a be all and end all of value, which is why there are 2 types of WAR for non-pitchers and they're still most useful only when comparing players who play the same position.

More importantly, the point of hockey is ultimately goals, and even over a period of 40 games or so, that is still greatly influenced by chance. Just like Alexander Steen most likely isn't going to shoot 20+ % over the course of the NHL season (at least not when all past seasons indicate his true talent lies around 10%) Cornell most likely is not going to shoot 14% overall and 24% on the power play all year. But if they do, well then getting outshot probably won't matter as much as it will if those numbers come back to earth.

All true ... but I didn't say it was useless, just that it's not very useful - particularly when rating individual players. People - not you - tend to exaggerate the importance of these numbers in determining an individual players' worth. More context will help, and it's getting there. You are correct about WAR - but WAR is pretty advanced compared to, say, OPS - or even Bill James' original Runs Created formula, and is therefore open to more subjective factors on what to weigh and how. The first "Advanced" baseball stats - like simple OPS - is a pretty rock solid indicator (adjusting for park factors, etc...) - whereas this is hockey's first "advanced" metric, and there's already too many holes in it. When Bill James first started writing Abstracts, his new way of looking at things were actually really obvious, if you just looked. He elegantly explained them, and his "formulas" were all simple and could be proven effective - almost like a mathematical proof. This can't done with hockey stats.

It's been said that plus-minus is not as good as Corsi because it's based on too small a sample size - yet plus-minus is at least measuring the exact thing we want to measure - goals. Whereas Corsi is only measuring things that may or may not lead to an actual goal. A double is a direct building block of scoring a run. Whereas a shot is not a building block of a goal, but rather a component of scoring a goal - there's a difference.

My point about not shooting more is not just about controlling overall shots - but about shot placement. Studies have been done to show different shooting percentages from different areas of the rink - so clearly, where you shoot from is pretty important - which makes obvious intuitive sense as well. If you hold onto the puck longer to set up more high percentage shots, then you may have less shots overall, but more high percentage ones.

Guy Gadowsky's teams tend to shoot from all over the place and rack up a zillion shots. Schafer's teams tend to be more in control - work it along the wall for an hour and a half before finally getting a shot off. Both ways can work. It depends.

Neither side is taking the extreme position the other is implying. Is anybody saying Hockey Analytics are worthless? Is anybody saying they are definitive?

It's early days for HA -- about 20 years of real work, the equivalent of the 1980s for baseball. Also, hockey's fluidity is much harder to model than baseball's discrete events.

It will be interesting to see how coaches develop counter-measures to HA-derived strategies (if this isn't happening already). Any lesson that applies to offense applies equally to defense.

There are people who say ... "so-and-so has a Corsi of X, he's terrible" - or "he's great" - and use it to prove one player is better than another. I see that all the time.

adamw
There are people who say ... "so-and-so has a Corsi of X, he's terrible" - or "he's great" - and use it to prove one player is better than another. I see that all the time.

Those people are idiots. I don't think the people here are idiots.

Trotsky

adamw
There are people who say ... "so-and-so has a Corsi of X, he's terrible" - or "he's great" - and use it to prove one player is better than another. I see that all the time.

Those people are idiots. I don't think the people here are idiots.

I think I made it clear I wasn't referring to anyone here

css228
Even WAR is not a be all and end all of value, which is why there are 2 types of WAR for non-pitchers and they're still most useful only when comparing players who play the same position.

Assuming you're talking about fWAR and rWAR, there are two types because two different entities set out to create a metric that "attempts to encapsulate a player’s total value to their team in one stat" (in other words, it IS supposed to be a be all and end all, it's just imperfect at this point) and went about it somewhat differently.

Trotsky
Also, hockey's fluidity is much harder to model than baseball's discrete events.

In hockey (and other similar sports, such as soccer, lacrosse, field hockey, and even basketball) offense and defense are also much more "integrated" than they are in baseball. Trying more home run passes in hockey necessarily means your forwards are not backchecking as effectively, and vice versa - if your forwards are down low, they're not going to be in a position for receiving clean breakout passes at speed. Pinching the defensemen helps the offense but hurts the defense, etc. In baseball, swinging for the fences has no effect on your ability to turn a double play later on, with the possible artificial linkage of salary limitations (you may not be able to afford golden glove defenders who are also fantastic hitters). Being good at hockey requires a much more delicate balance between offense and defense, because they are tightly integrated into a single game.

adamw
There are people who say ... "so-and-so has a Corsi of X, he's terrible" - or "he's great" - and use it to prove one player is better than another. I see that all the time.

Absolutely, the numbers are irrelevant on an individual level without looking at zone starts, quality of competition, and quality of teammates, but those can all be factored into different variants of Corsi. I'm not saying Sean Couturier is great because he has a good Corsi, I'm saying he's great because last year he had a great Corsi despite playing the the best competition available with nearly 60% defensive zone starts and four of his five most common linemates being Max Talbot, Mike Knuble, Zac Rinaldo, and Ruslan Fedetenko. Justin Williams is really nice player, but he's only leading the NHL in Corsi % because his linemates are Dustin Brown and Anze Kopitar.

css228
Absolutely, the numbers are irrelevant on an individual level without looking at zone starts, quality of competition, and quality of teammates, but those can all be factored into different variants of Corsi. I'm not saying Sean Couturier is great because he has a good Corsi, I'm saying he's great because last year he had a great Corsi despite playing the the best competition available with nearly 60% defensive zone starts and four of his five most common linemates being Max Talbot, Mike Knuble, Zac Rinaldo, and Ruslan Fedetenko. Justin Williams is really nice player, but he's only leading the NHL in Corsi % because his linemates are Dustin Brown and Anze Kopitar.

No doubt. But can't the same be said for plus-minus? Which is also a more direct correlation to actual goals? You can make all sorts of +/- adjustments to better account of those things too, and in the end, have something more directly useful. Yet Corsi-ites poo-poo +/- as kind of a joke.

Josh '99

css228
Even WAR is not a be all and end all of value, which is why there are 2 types of WAR for non-pitchers and they're still most useful only when comparing players who play the same position.

Assuming you're talking about fWAR and rWAR, there are two types because two different entities set out to create a metric that "attempts to encapsulate a player’s total value to their team in one stat" (in other words, it IS supposed to be a be all and end all, it's just imperfect at this point) and went about it somewhat differently.

Yeah I guess that one is, but it still can't really be compared across positions, even with the positional adjustments. Not to mention Pitcher WAR and regular WAR are calculated so differently that you can't really compare the value of a pitcher to an everyday player.

css228
I'm not saying Sean Couturier is great because he has a good Corsi, I'm saying he's great because last year he had a great Corsi despite playing the the best competition available with nearly 60% defensive zone starts and four of his five most common linemates being Max Talbot, Mike Knuble, Zac Rinaldo, and Ruslan Fedetenko.

I think he's a good player just based on what I've seen - but aren't you basing the "competition" factor on opponents' Corsi, which just makes it self-referential? That only works if you assume Corsi is a measure of a quality in the first place.

It seems to me that the key to a good statistic is how long does it take to show a meaningful difference. If it takes an 80 game season to show a marginal difference between 2 players, then it's not going to be very useful in our game. If you have something that can show a difference in 20 games, then go for it. Anything less than that may not be better than just what a coach thinks. I'm sure that with time better stats, useful to the college game, will come out. I'm just not sure I'm going to see it in my viewing lifetime. So for now, I'll be happy just cheering.

adamw

css228
Absolutely, the numbers are irrelevant on an individual level without looking at zone starts, quality of competition, and quality of teammates, but those can all be factored into different variants of Corsi. I'm not saying Sean Couturier is great because he has a good Corsi, I'm saying he's great because last year he had a great Corsi despite playing the the best competition available with nearly 60% defensive zone starts and four of his five most common linemates being Max Talbot, Mike Knuble, Zac Rinaldo, and Ruslan Fedetenko. Justin Williams is really nice player, but he's only leading the NHL in Corsi % because his linemates are Dustin Brown and Anze Kopitar.

No doubt. But can't the same be said for plus-minus? Which is also a more direct correlation to actual goals? You can make all sorts of +/- adjustments to better account of those things too, and in the end, have something more directly useful. Yet Corsi-ites poo-poo +/- as kind of a joke.

It's just that the sample size on +/- is so small because goals are such a rare event. They occur on less than 10% of shots, so a player having just stepped out on a bad change that wasn't really his fault, that's going to bias the results more than a single shot attempt off of a bad change. Furthermore, shot attempts are more directly in the control of the skaters, whereas a bad goalie can really hurt a players +/-. Crazy bounces have much more effect on +/-. The sample size on goals is just too small for it to have any useful predictive value. Think of it like Defense Independent Pitching Statistics like FIP, which seek to eliminate the effects defenses have on a pitchers numbers. Hockey is more fluid, so its difficult, but at least Corsi and Fenwick attempting to do something +/- can't really do by increasing the sample size and focusing on the events skaters have the most control over. For the record, I think Fenwick is far more valuable as a predictive tool than Corsi, because shot-blocking is a skill representative of good defensive positioning.

Right ... I'm just saying that plus-minus directly counts a result that has to do with winning and losing ... whereas the connection of Fenwick/Corsi to winning and losing is more tenuous and indirect - however much it may correlate. So that would seem to offset.

Despite the correlation, it's hard to measure the effect a shot has on creating an actual goal. There's so many other factors that play into scoring a goal - quality of goalie, where the shot was taken from, luck, and so on. Whereas with baseball stats, you can directly measure the increase in likelihood of scoring a run based upon whether you got a single, double, out, etc...

adamw

css228
I'm not saying Sean Couturier is great because he has a good Corsi, I'm saying he's great because last year he had a great Corsi despite playing the the best competition available with nearly 60% defensive zone starts and four of his five most common linemates being Max Talbot, Mike Knuble, Zac Rinaldo, and Ruslan Fedetenko.

I think he's a good player just based on what I've seen - but aren't you basing the "competition" factor on opponents' Corsi, which just makes it self-referential? That only works if you assume Corsi is a measure of a quality in the first place.

It's a measure of possession ability rather than quality. I think that Corsi describes what is occurring on the ice when a player is out there. Corsi doesn't really tell me that Couturier is valuable as much as it tells me that when he is on the ice, the Flyers outshoot their opponents more often than not. What QOC tells me is whether or not the players he's going against tend to outshoot their competition when their on the ice. So really what I should say we've learned is that when Couturier is on the ice, the Flyers tend to get the majority of the shots, despite the fact he plays against competition that usually gets the majority of the shots when they are on the ice, and the fact that he is playing with players who do not tend to outshoot their opponents when they are not playing with Couturier. In other words, not matter who Couturier is against, the puck tends to end up in the offensive zone, even though he plays against competition that tends to accomplish that themselves. This is a much more measured statement than what I said before, and I think it lays out the logic of my thought process on QOC. You can imply whatever amount of value you like from that, but I happen to believe that matters.

adamw
There's so many other factors that play into scoring a goal - quality of goalie, where the shot was taken from, luck, and so on.

Which is why +/- is such a bad statistic. On a team level sure, goal differential matters, but its like goalie wins, it accounts for a lot of factors which are completely out of a players control and due to chance. What you seem to be taking issue with overall is the correlation between puck possession and winning via goal scoring. I think you're right that probably does need to be explored more deeply, though since I believe a lot of hockey comes down to random chance and the puck sitting right in any given game, I tend to think about good process leading to good long term results. When so much is dependent on chance, the team with more balls in the lottery draw has better odds of winning. It does not mean they will win every time, because good process doesn't guarantee good results. However, even if there is reason to believe that maybe the correlation isn't causal, that doesn't mean that +/- is in anyway a stat that doesn't belong on the scrap heap along with saves, pitcher wins/losses, and goalie wins/losses.

Ultimately, I think this really comes down to whether or not you believe that a quality shot and scoring is a consistently reproducible and significant phenomenon across the team from game to game, in the sense that a team can play a certain why that they may take fewer shots, but almost all of their shots are quality. I've seen no evidence to believe that it is, at least on the team level.

adamw
Here is the main difference between OPS and Corsi. OPS is a direct building block to scoring runs. You would never tell a baseball player "get on base less" or "please hit home runs only to this spot, or at this time". Whereas with shots ... you can't say that the solution to improving your game is simply shooting the puck more. That may or may not be the case, but you can't know that.

Really nit-picking here, but the purpose of the sacrifice bunt is to give up trying to get on base to move base runners over.

KGR11

adamw
Here is the main difference between OPS and Corsi. OPS is a direct building block to scoring runs. You would never tell a baseball player "get on base less" or "please hit home runs only to this spot, or at this time". Whereas with shots ... you can't say that the solution to improving your game is simply shooting the puck more. That may or may not be the case, but you can't know that.

Really nit-picking here, but the purpose of the sacrifice bunt is to give up trying to get on base to move base runners over.

And the sacrifice bunt is a stupid play which lowers run expectancy. Years of studies have consistently shown that you can expect to score more runs per inning with no outs and a runner on first than 1 out and a runner on 2nd. There may be some situations with particular hitters when a sacrifice bunt might increase run expectancy (e.g. pitchers), but overall its dumb and shouldn't be done.

KGR11
Really nit-picking here, but the purpose of the sacrifice bunt is to give up trying to get on base to move base runners over.

Yeah, that's really nitpicking, because you know what I meant That, and what css228 said.

I don't think I've ever wanted an "ignore thread" option as much as I do now.

css228

KGR11

adamw
Here is the main difference between OPS and Corsi. OPS is a direct building block to scoring runs. You would never tell a baseball player "get on base less" or "please hit home runs only to this spot, or at this time". Whereas with shots ... you can't say that the solution to improving your game is simply shooting the puck more. That may or may not be the case, but you can't know that.

Really nit-picking here, but the purpose of the sacrifice bunt is to give up trying to get on base to move base runners over.

And the sacrifice bunt is a stupid play which lowers run expectancy. Years of studies have consistently shown that you can expect to score more runs per inning with no outs and a runner on first than 1 out and a runner on 2nd. There may be some situations with particular hitters when a sacrifice bunt might increase run expectancy (e.g. pitchers), but overall its dumb and shouldn't be done.

Here in a nutshell is what is wrong with sports analytics. (I'm picking on your post and sorry for that!) There are studies that show that bunting leads to a lower run expectancy and you take that study and jump to "it's dumb and shouldn't be done". There's a tendency for people who are advocates of analytics to put too much faith in the results of the studies. This sometimes means you miss the nuances of how to apply what you' learned from the studies. There's an even greater tendency to take on an attitude of "whoever doesn't follow analytics is dumb", which is especially prevalent when simultaneously missing the nuances.

Using your bunting example, I generally agree that bunting is a poor decision. But there are times where it makes sense: bad hitter, bad hitter-pitcher matchup, ground ball pitcher with slow batter meaning higher probability of double play, late inning situation where one run is vastly more important than multiple runs. I suspect that a sufficiently detailed study would capture some of these effects when you can get enough sample size. But I routinely see people using the general purpose run expectancy of a bunt as reason to toss insults at any manager who employs it (or fans who support the idea).

Analytics are a useful tool but need to be used in the proper context. Since hockey is a sport that is more difficult to analyze and anlytics are their infancy we shoud be especially careful abo drawing strong conclusions.

css228
And the sacrifice bunt is a stupid play which lowers run expectancy. Years of studies have consistently shown that you can expect to score more runs per inning with no outs and a runner on first than 1 out and a runner on 2nd. There may be some situations with particular hitters when a sacrifice bunt might increase run expectancy (e.g. pitchers), but overall its dumb and shouldn't be done.

I played in an adult baseball league a couple years ago ... and every time we got 1st and 2nd nobody out, some dude who played D-I baseball in college would yell and scream that we should be bunting - because one time, we grounded into a DP. I thought we were going to get into blows because I kept telling him he didn't know what he was talking about. I considered sending him all the math on the topic, but eventually said screw it.

But there's a good example where you can take a baseball event, and directly measure its effect on the thing that's most important -- scoring runs. Hockey is not there yet. But I appreciate everything you've said, and appreciate you acknowledging some of what I'm saying.

KeithK
Analytics are a useful tool but need to be used in the proper context. Since hockey is a sport that is more difficult to analyze and anlytics are their infancy we shoud be especially careful abo drawing strong conclusions.

Right on Keith - that's exactly what I've been saying. Stats are stats - it's how you use them. I don't doubt that Fenwick generally demonstrates what it's intending to demonstrate. But what is it really telling us about the *ability* to score a goal, or ability of a certain player, or informing us of what strategy to use. We don't fully know yet.

Another example is carrying the puck over the line vs. dumping. Metrics tell you that carrying the puck into the zone leads to more shots. So - does that mean everyone should carry the puck in, or carry it all the time? Heck no. There's too many factors. Yet, with baseball metrics, it's often pretty obvious what the decision should be, based upon the situation. It's more solveable.

adamw

css228
And the sacrifice bunt is a stupid play which lowers run expectancy. Years of studies have consistently shown that you can expect to score more runs per inning with no outs and a runner on first than 1 out and a runner on 2nd. There may be some situations with particular hitters when a sacrifice bunt might increase run expectancy (e.g. pitchers), but overall its dumb and shouldn't be done.

I played in an adult baseball league a couple years ago ... and every time we got 1st and 2nd nobody out, some dude who played D-I baseball in college would yell and scream that we should be bunting - because one time, we grounded into a DP. I thought we were going to get into blows because I kept telling him he didn't know what he was talking about. I considered sending him all the math on the topic, but eventually said screw it.

But there's a good example where you can take a baseball event, and directly measure its effect on the thing that's most important -- scoring runs. Hockey is not there yet. But I appreciate everything you've said, and appreciate you acknowledging some of what I'm saying.

Two more reasons why bunting is lame.

1) Often, it's done after a pitcher's gotten himself into trouble with zero outs. Why give him an out? Most of the "math" doesn't factor in that if a pitcher's let two straight guys on, he might be off his game at that particular moment.

2) The math also usually assumes bunts have a 100% success rate. It's 1 out, guy on 2nd versus 0 out, guy on 1st. There's no consideration of the hitter maybe failing to get a bunt down.

This isn't to say never sac bunt. Just, do it less.

css228

Josh '99

css228
Even WAR is not a be all and end all of value, which is why there are 2 types of WAR for non-pitchers and they're still most useful only when comparing players who play the same position.

Assuming you're talking about fWAR and rWAR, there are two types because two different entities set out to create a metric that "attempts to encapsulate a player’s total value to their team in one stat" (in other words, it IS supposed to be a be all and end all, it's just imperfect at this point) and went about it somewhat differently.

Yeah I guess that one is, but it still can't really be compared across positions, even with the positional adjustments. Not to mention Pitcher WAR and regular WAR are calculated so differently that you can't really compare the value of a pitcher to an everyday player.

That's true, but I think that goes to the fact that the metric just isn't good enough to make those kinds of comparisons yet.

It's a fairly meaningless hair we're splitting here though. I think you're right in general that almost anything you'd look at is still just a piece of the puzzle.

adamw

Another example is carrying the puck over the line vs. dumping. Metrics tell you that carrying the puck into the zone leads to more shots. So - does that mean everyone should carry the puck in, or carry it all the time? Heck no. There's too many factors. Yet, with baseball metrics, it's often pretty obvious what the decision should be, based upon the situation. It's more solveable.

Well that's the heart of it, right? Situational analysis is much easier in baseball, simply because there are many more easily-definable situations. With no clock, one can take stock and neatly define the situation before each pitch and use it as a data point. Hockey, basketball, soccer, et al. are nearly always in motion so there are fewer opportunities to define a pre-play situation, as well as fewer measurable and reducable variables.

Don't feel like responding to a particular post but ... tell me where I'm wrong:

From what I've read here, Corsi sounds like a stat that is descriptive, and useful for describing the past (and evaluating player/team quality), but not something that can be used to make specific improvements. I suppose you could juke the stat by SHOOOOOOOOOOOOOOOTing more, but what kind of chaos-motivated person would go about trying to juke the stat at the expense of winning? (Even in an arbitration year, you'll end up a healthy scratch with a high corsi because your coach thinks you are an imbecile.) So, since you want to take good shots, you take the shots that are there and the shots act as a proxy for possession, letting the world know who had the most opportunities. It isn't useful for improvement because the stat doesn't tell you how to get more shots, only that - if your corsi sucks - what you are doing isn't working and you should probably watch more tape.

So while the discussion shouldn't begin and end with corsi/fenwick it is a much better starting point than where hockey was before it was developed, no?

ugarte
Don't feel like responding to a particular post but ... tell me where I'm wrong:

From what I've read here, Corsi sounds like a stat that is descriptive, and useful for describing the past (and evaluating player/team quality), but not something that can be used to make specific improvements. I suppose you could juke the stat by SHOOOOOOOOOOOOOOOTing more, but what kind of chaos-motivated person would go about trying to juke the stat at the expense of winning? (Even in an arbitration year, you'll end up a healthy scratch with a high corsi because your coach thinks you are an imbecile.) So, since you want to take good shots, you take the shots that are there and the shots act as a proxy for possession, letting the world know who had the most opportunities. It isn't useful for improvement because the stat doesn't tell you how to get more shots, only that - if your corsi sucks - what you are doing isn't working and you should probably watch more tape.

So while the discussion shouldn't begin and end with corsi/fenwick it is a much better starting point than where hockey was before it was developed, no?

It is in my opinion a very good starting point, and I believe it does have some predictive value (especially fenwick) in that it indicates a process that is conducive to winning. But some here may think that is too strong a conclusion to draw.

Maple Leafs Update. Not really looking good recently. Can't shoot 10%+ forever.

From Grantland, a general article on puck possession and zone entry. No equations or other hard math .

The gist of the story in [www.grantland.com]

Sean McIndoe, Grantland.com
If you're familiar with advanced stats, you know how much emphasis they place on possession. In the case of dump-in vs. carry, you might suspect that that gives away the answer, and you'd be right. It turns out that crossing the blue line with possession is worth more than a dump-in ... How much more? Quite a bit, according to this paper presented at the 2013 MIT Sloan Sports Analytics Conference. After tracking more than 300 games from the 2011-12 season, the authors found that, even when accounting for the higher failure rate of carry attempts, that approach still generated roughly twice as many shots, scoring chances, and goals as dumping in the puck and trying to retrieve it.

... So a clean zone entry requires some skill, and skill isn't a quality that's distributed equally among NHL players. It may make perfect sense to have less-skilled guys who make up the league's third and fourth lines keeping shooting it in, especially when a team is defending a lead.

... Are any NHL teams changing their strategy based on this kind of thinking? Yes, as it turns out. One prominent example: the Minnesota Wild, a classic dump-and-chase team last year that made the playoffs with that style of play. But after the Wild realized they were going to need to beat elite divisional rivals like the Blackhawks and Blues to get to the next level, the Minnesota brain trust decided to shift strategies. As outlined in this recent post by Elliotte Friedman, Minnesota has decided to focus on gaining the zone with the puck.

Interesting article on movement to detailed video analytics in ice hockey: FiveThirtyEight article "The People Pushing the NHL Into the Advanced Stats Era"

ERIC TULSKY
...
Tracking by Schmidt and others has helped explain that a team’s entry into the offensive zone has a big impact on its shot differential. Carrying the puck into the offensive zone leads to more than twice as many shots and goals as a dump-and-chase play does, even after removing plays like odd-man rushes and dump-ins that are made just to buy time for a line change. These results have even made an impact on strategy.

Schmidt’s data from this season allows us to evaluate individual defensive contributions for the first time, which we couldn’t do with traditional box scores. ...

profudge
Interesting article on movement to detailed video analytics in ice hockey: FiveThirtyEight article "The People Pushing the NHL Into the Advanced Stats Era"

ERIC TULSKY
...
Tracking by Schmidt and others has helped explain that a team’s entry into the offensive zone has a big impact on its shot differential. Carrying the puck into the offensive zone leads to more than twice as many shots and goals as a dump-and-chase play does, even after removing plays like odd-man rushes and dump-ins that are made just to buy time for a line change. These results have even made an impact on strategy.

Schmidt’s data from this season allows us to evaluate individual defensive contributions for the first time, which we couldn’t do with traditional box scores. ...

Dumb question: why have people tracking and recording visually? Why not just stick an RFID on every player, stream the whole thing to a hard drive, and use software to analyze it?

You'd have to stick one on the puck too, right?

Trotsky

profudge
Interesting article on movement to detailed video analytics in ice hockey: FiveThirtyEight article "The People Pushing the NHL Into the Advanced Stats Era"

ERIC TULSKY
...
Tracking by Schmidt and others has helped explain that a team’s entry into the offensive zone has a big impact on its shot differential. Carrying the puck into the offensive zone leads to more than twice as many shots and goals as a dump-and-chase play does, even after removing plays like odd-man rushes and dump-ins that are made just to buy time for a line change. These results have even made an impact on strategy.

Schmidt’s data from this season allows us to evaluate individual defensive contributions for the first time, which we couldn’t do with traditional box scores. ...

Dumb question: why have people tracking and recording visually? Why not just stick an RFID on every player, stream the whole thing to a hard drive, and use software to analyze it?

Could happen at some point. But you'd need to get the entire league and players to buy into it before it could happen. Plus develop the software to make sense of the flood of data. It's simpler for a team to pay someone peanuts to hart games as a starting point, at least.

KeithK
Could happen at some point. But you'd need to get the entire league and players to buy into it before it could happen. Plus develop the software to make sense of the flood of data. It's simpler for a team to pay someone peanuts to hart games as a starting point, at least.

You only really need to convince the league office. The players don't get a vote and why would they care either way?

I doubt the software would be a problem. They track elk herds and ocean buoys and any number of things that are far more complicated than 40 or so objects moving slowly around a formally bounded, two-dimensional space. And at first you really would only be tracking a limited number of states like zone and very few properties like time. It sounds like a senior thesis; not even grad school work.

I also doubt it would be expensive. It seems like 1990s technology, and from a data gathering and analysis perspective it's nothing compared to weather simulations or even extant game engines.

It seems really easy and really cheap.

Trotsky

KeithK
Could happen at some point. But you'd need to get the entire league and players to buy into it before it could happen. Plus develop the software to make sense of the flood of data. It's simpler for a team to pay someone peanuts to hart games as a starting point, at least.

You only really need to convince the league office. The players don't get a vote and why would they care either way?

I doubt the software would be a problem. They track elk herds and ocean buoys and any number of things that are far more complicated than 40 or so objects moving slowly around a formally bounded, two-dimensional space. And at first you really would only be tracking a limited number of states like zone and very few properties like time. It sounds like a senior thesis; not even grad school work.

I also doubt it would be expensive. It seems like 1990s technology, and from a data gathering and analysis perspective it's nothing compared to weather simulations or even extant game engines.

It seems really easy and really cheap.

I would think that anything affecting the players (adding RFIDs to their uniforms) would require player approval. It certainly would in baseball, which is what I am most famiiar with. Why would they care? No idea. But players unions have made a stink about stupid things before.

I don't disagree that this wouldn't be that hard to implement. but it would require some effort to organize and push, which mht not exist. Particularly since there are probably some teams that aren't particuarly interested in analytics at this point. Also I can easily see a team that is interested in analytics being more willing to develop their own, admittedly inferior, data manually to avoid keep it in house and keep it as a proprietary advantage.

The article I referenced above discusses the RFID chip in the puck, but also says for complete analysis would need a chip in each players stick also.

The data being recorded for the Flyers and the author on offensive zone entry is done by a volunteer currently.

Trotsky
You only really need to convince the league office. The players don't get a vote...

Left-wing fanatic forgets about unions. News at 11.

ugarte

Trotsky
You only really need to convince the league office. The players don't get a vote...

Left-wing fanatic forgets about unions. News at 11.

Actually, I was thinking right-wing fanatics would complain that RFID chips are a gateway to the World Gummint.

And anyway, I was thinking about colleges, which have slave labor.

Trotsky

profudge
Interesting article on movement to detailed video analytics in ice hockey: FiveThirtyEight article "The People Pushing the NHL Into the Advanced Stats Era"

ERIC TULSKY
...
Tracking by Schmidt and others has helped explain that a team’s entry into the offensive zone has a big impact on its shot differential. Carrying the puck into the offensive zone leads to more than twice as many shots and goals as a dump-and-chase play does, even after removing plays like odd-man rushes and dump-ins that are made just to buy time for a line change. These results have even made an impact on strategy.

Schmidt’s data from this season allows us to evaluate individual defensive contributions for the first time, which we couldn’t do with traditional box scores. ...

Dumb question: why have people tracking and recording visually? Why not just stick an RFID on every player, stream the whole thing to a hard drive, and use software to analyze it?

But why not do it visually? You just have to record the entire rink. If intelligence satellites can have a resolution as fine as 10 cm, four rink-side cameras should be more than adequate.

Of course, if Redcast runs the cameras, all bets are off.

Swampy

Trotsky

profudge
Interesting article on movement to detailed video analytics in ice hockey: FiveThirtyEight article "The People Pushing the NHL Into the Advanced Stats Era"

ERIC TULSKY
...
Tracking by Schmidt and others has helped explain that a team’s entry into the offensive zone has a big impact on its shot differential. Carrying the puck into the offensive zone leads to more than twice as many shots and goals as a dump-and-chase play does, even after removing plays like odd-man rushes and dump-ins that are made just to buy time for a line change. These results have even made an impact on strategy.

Schmidt’s data from this season allows us to evaluate individual defensive contributions for the first time, which we couldn’t do with traditional box scores. ...

Dumb question: why have people tracking and recording visually? Why not just stick an RFID on every player, stream the whole thing to a hard drive, and use software to analyze it?

But why not do it visually? You just have to record the entire rink. If intelligence satellites can have a resolution as fine as 10 cm, four rink-side cameras should be more than adequate.

Of course, if Redcast runs the cameras, all bets are off.

Even with the right camera setup and appropriate analysis, you'd still eventually wind up, more or less, with similar data to what you'd get through RFID tracking. Why perform the extra steps if you don't need to?

Josh '99

Swampy

Trotsky

profudge
Interesting article on movement to detailed video analytics in ice hockey: FiveThirtyEight article "The People Pushing the NHL Into the Advanced Stats Era"

ERIC TULSKY
...
Tracking by Schmidt and others has helped explain that a team’s entry into the offensive zone has a big impact on its shot differential. Carrying the puck into the offensive zone leads to more than twice as many shots and goals as a dump-and-chase play does, even after removing plays like odd-man rushes and dump-ins that are made just to buy time for a line change. These results have even made an impact on strategy.

Schmidt’s data from this season allows us to evaluate individual defensive contributions for the first time, which we couldn’t do with traditional box scores. ...

Dumb question: why have people tracking and recording visually? Why not just stick an RFID on every player, stream the whole thing to a hard drive, and use software to analyze it?

But why not do it visually? You just have to record the entire rink. If intelligence satellites can have a resolution as fine as 10 cm, four rink-side cameras should be more than adequate.

Of course, if Redcast runs the cameras, all bets are off.

Even with the right camera setup and appropriate analysis, you'd still eventually wind up, more or less, with similar data to what you'd get through RFID tracking. Why perform the extra steps if you don't need to?

Because you wouldn't have to perform the extra steps of outfitting the players and pucks with RFID devices. Cameras and image processing software are way cheaper, and to a large degree, already exist at the rinks.

Trotsky

profudge
Interesting article on movement to detailed video analytics in ice hockey: FiveThirtyEight article "The People Pushing the NHL Into the Advanced Stats Era"

ERIC TULSKY
...
Tracking by Schmidt and others has helped explain that a team’s entry into the offensive zone has a big impact on its shot differential. Carrying the puck into the offensive zone leads to more than twice as many shots and goals as a dump-and-chase play does, even after removing plays like odd-man rushes and dump-ins that are made just to buy time for a line change. These results have even made an impact on strategy.

Schmidt’s data from this season allows us to evaluate individual defensive contributions for the first time, which we couldn’t do with traditional box scores. ...

Dumb question: why have people tracking and recording visually? Why not just stick an RFID on every player, stream the whole thing to a hard drive, and use software to analyze it?

E-Z Pass, E-Z Score.

Robb

Josh '99

Swampy

Trotsky

profudge
Interesting article on movement to detailed video analytics in ice hockey: FiveThirtyEight article "The People Pushing the NHL Into the Advanced Stats Era"

ERIC TULSKY
...
Tracking by Schmidt and others has helped explain that a team’s entry into the offensive zone has a big impact on its shot differential. Carrying the puck into the offensive zone leads to more than twice as many shots and goals as a dump-and-chase play does, even after removing plays like odd-man rushes and dump-ins that are made just to buy time for a line change. These results have even made an impact on strategy.

Schmidt’s data from this season allows us to evaluate individual defensive contributions for the first time, which we couldn’t do with traditional box scores. ...

Dumb question: why have people tracking and recording visually? Why not just stick an RFID on every player, stream the whole thing to a hard drive, and use software to analyze it?

But why not do it visually? You just have to record the entire rink. If intelligence satellites can have a resolution as fine as 10 cm, four rink-side cameras should be more than adequate.

Of course, if Redcast runs the cameras, all bets are off.

Even with the right camera setup and appropriate analysis, you'd still eventually wind up, more or less, with similar data to what you'd get through RFID tracking. Why perform the extra steps if you don't need to?

Because you wouldn't have to perform the extra steps of outfitting the players and pucks with RFID devices. Cameras and image processing software are way cheaper, and to a large degree, already exist at the rinks.

I don't know that the processing software is necessarily cheaper. The NBA's system is patented and they (presumably) pay a licensing fee to use it. Other companies also have patents and, I can tell you from firsthand experience, are actively developing technology in this area. ESPN (i.e. Disney, known for aggressively protecting their IP), it seems to me, isn't likely to just let the NHL use their proprietary technology out of the goodness of their collective corporate heart. (Not to say that they couldn't run into the same issues with an RFID-based solution, of course.) There are also physical barriers to entry, albeit fairly low ones, in that the NBA's system uses dedicated cameras and implementing a similar system for hockey games would require its own cameras because of the larger field of view that needs to be covered.

Josh '99

Robb

Josh '99

Swampy

Trotsky

profudge
Interesting article on movement to detailed video analytics in ice hockey: FiveThirtyEight article "The People Pushing the NHL Into the Advanced Stats Era"

ERIC TULSKY
...
Tracking by Schmidt and others has helped explain that a team’s entry into the offensive zone has a big impact on its shot differential. Carrying the puck into the offensive zone leads to more than twice as many shots and goals as a dump-and-chase play does, even after removing plays like odd-man rushes and dump-ins that are made just to buy time for a line change. These results have even made an impact on strategy.

Schmidt’s data from this season allows us to evaluate individual defensive contributions for the first time, which we couldn’t do with traditional box scores. ...

Dumb question: why have people tracking and recording visually? Why not just stick an RFID on every player, stream the whole thing to a hard drive, and use software to analyze it?

But why not do it visually? You just have to record the entire rink. If intelligence satellites can have a resolution as fine as 10 cm, four rink-side cameras should be more than adequate.

Of course, if Redcast runs the cameras, all bets are off.

Even with the right camera setup and appropriate analysis, you'd still eventually wind up, more or less, with similar data to what you'd get through RFID tracking. Why perform the extra steps if you don't need to?

Because you wouldn't have to perform the extra steps of outfitting the players and pucks with RFID devices. Cameras and image processing software are way cheaper, and to a large degree, already exist at the rinks.

I don't know that the processing software is necessarily cheaper. The NBA's system is patented and they (presumably) pay a licensing fee to use it. Other companies also have patents and, I can tell you from firsthand experience, are actively developing technology in this area. ESPN (i.e. Disney, known for aggressively protecting their IP), it seems to me, isn't likely to just let the NHL use their proprietary technology out of the goodness of their collective corporate heart. (Not to say that they couldn't run into the same issues with an RFID-based solution, of course.) There are also physical barriers to entry, albeit fairly low ones, in that the NBA's system uses dedicated cameras and implementing a similar system for hockey games would require its own cameras because of the larger field of view that needs to be covered.

But I see at least two advantages.

First, any individual program can implement a video solution, at least for home games. One doesn't need the agreement of the league, NC$$, etc.

Second, coaches watch film anyway. So besides possibly already having the equipment and raw material for analysis, consider the development process. Take, for example, crossing the blue line with the puck rather than dumping it in. The problem is there are all kinds of ways to cross the blue line with puck possession:

1. By hanging at the opponent's blue line and waiting to receive a long pass, as part of team strategy.
2. By checking and causing a turnaround in the neutral zone.
3. By beating a man in the neutral zone.
4. By breaking out as a team from its own defensive end.
5. Etc.

In order to decipher this and develop software able to distinguish important differences in variants of something as deceptively simple as crossing the blue line with possession, the developer will likely want to review videos in order to see what was really going on. One might even want a professional hockey coach to distinguish different situations. In the early development stages one would almost certainly want to compare the computer-analyzed data with visual examination of game films in order to ensure that the software is picking up all the important nuances, etc.

So since the developer is going to use video anyway, this approach seems more efficient.

Swampy

Josh '99

Robb

Josh '99

Swampy

Trotsky

profudge
Interesting article on movement to detailed video analytics in ice hockey: FiveThirtyEight article "The People Pushing the NHL Into the Advanced Stats Era"

ERIC TULSKY
...
Tracking by Schmidt and others has helped explain that a team’s entry into the offensive zone has a big impact on its shot differential. Carrying the puck into the offensive zone leads to more than twice as many shots and goals as a dump-and-chase play does, even after removing plays like odd-man rushes and dump-ins that are made just to buy time for a line change. These results have even made an impact on strategy.

Schmidt’s data from this season allows us to evaluate individual defensive contributions for the first time, which we couldn’t do with traditional box scores. ...

Dumb question: why have people tracking and recording visually? Why not just stick an RFID on every player, stream the whole thing to a hard drive, and use software to analyze it?

But why not do it visually? You just have to record the entire rink. If intelligence satellites can have a resolution as fine as 10 cm, four rink-side cameras should be more than adequate.

Of course, if Redcast runs the cameras, all bets are off.

Even with the right camera setup and appropriate analysis, you'd still eventually wind up, more or less, with similar data to what you'd get through RFID tracking. Why perform the extra steps if you don't need to?

Because you wouldn't have to perform the extra steps of outfitting the players and pucks with RFID devices. Cameras and image processing software are way cheaper, and to a large degree, already exist at the rinks.

I don't know that the processing software is necessarily cheaper. The NBA's system is patented and they (presumably) pay a licensing fee to use it. Other companies also have patents and, I can tell you from firsthand experience, are actively developing technology in this area. ESPN (i.e. Disney, known for aggressively protecting their IP), it seems to me, isn't likely to just let the NHL use their proprietary technology out of the goodness of their collective corporate heart. (Not to say that they couldn't run into the same issues with an RFID-based solution, of course.) There are also physical barriers to entry, albeit fairly low ones, in that the NBA's system uses dedicated cameras and implementing a similar system for hockey games would require its own cameras because of the larger field of view that needs to be covered.

But I see at least two advantages.

First, any individual program can implement a video solution, at least for home games. One doesn't need the agreement of the league, NC$$, etc.

Second, coaches watch film anyway. So besides possibly already having the equipment and raw material for analysis, consider the development process. Take, for example, crossing the blue line with the puck rather than dumping it in. The problem is there are all kinds of ways to cross the blue line with puck possession:

1. By hanging at the opponent's blue line and waiting to receive a long pass, as part of team strategy.
2. By checking and causing a turnaround in the neutral zone.
3. By beating a man in the neutral zone.
4. By breaking out as a team from its own defensive end.
5. Etc.

In order to decipher this and develop software able to distinguish important differences in variants of something as deceptively simple as crossing the blue line with possession, the developer will likely want to review videos in order to see what was really going on. One might even want a professional hockey coach to distinguish different situations. In the early development stages one would almost certainly want to compare the computer-analyzed data with visual examination of game films in order to ensure that the software is picking up all the important nuances, etc.

So since the developer is going to use video anyway, this approach seems more efficient.

That's a fair point I didn't really consider. There are certainly added benefits to having the video that you don't get from a solely data-driven solution.

profudge
The article I referenced above discusses the RFID chip in the puck, but also says for complete analysis would need a chip in each players stick also.

Chiiiiiiiipless!
Chiiiiiiiipless!

Grosenick graduates writing hockey based thesis.

Give Oates credit for doing this before online classes.

Albany Times-Union
RPI great Adam Oates left Troy in 1985 for pro hockey and later got his degree in management, but he did it by returning to campus every summer for six years and physically sitting in a classroom. That's old school.

Josh '99

Swampy

Josh '99

Robb

Josh '99

Swampy

Trotsky

profudge
Interesting article on movement to detailed video analytics in ice hockey: FiveThirtyEight article "The People Pushing the NHL Into the Advanced Stats Era"

ERIC TULSKY
...
Tracking by Schmidt and others has helped explain that a team’s entry into the offensive zone has a big impact on its shot differential. Carrying the puck into the offensive zone leads to more than twice as many shots and goals as a dump-and-chase play does, even after removing plays like odd-man rushes and dump-ins that are made just to buy time for a line change. These results have even made an impact on strategy.

Schmidt’s data from this season allows us to evaluate individual defensive contributions for the first time, which we couldn’t do with traditional box scores. ...

Dumb question: why have people tracking and recording visually? Why not just stick an RFID on every player, stream the whole thing to a hard drive, and use software to analyze it?

But why not do it visually? You just have to record the entire rink. If intelligence satellites can have a resolution as fine as 10 cm, four rink-side cameras should be more than adequate.

Of course, if Redcast runs the cameras, all bets are off.

Even with the right camera setup and appropriate analysis, you'd still eventually wind up, more or less, with similar data to what you'd get through RFID tracking. Why perform the extra steps if you don't need to?

Because you wouldn't have to perform the extra steps of outfitting the players and pucks with RFID devices. Cameras and image processing software are way cheaper, and to a large degree, already exist at the rinks.

I don't know that the processing software is necessarily cheaper. The NBA's system is patented and they (presumably) pay a licensing fee to use it. Other companies also have patents and, I can tell you from firsthand experience, are actively developing technology in this area. ESPN (i.e. Disney, known for aggressively protecting their IP), it seems to me, isn't likely to just let the NHL use their proprietary technology out of the goodness of their collective corporate heart. (Not to say that they couldn't run into the same issues with an RFID-based solution, of course.) There are also physical barriers to entry, albeit fairly low ones, in that the NBA's system uses dedicated cameras and implementing a similar system for hockey games would require its own cameras because of the larger field of view that needs to be covered.

But I see at least two advantages.

First, any individual program can implement a video solution, at least for home games. One doesn't need the agreement of the league, NC$$, etc.

Second, coaches watch film anyway. So besides possibly already having the equipment and raw material for analysis, consider the development process. Take, for example, crossing the blue line with the puck rather than dumping it in. The problem is there are all kinds of ways to cross the blue line with puck possession:

1. By hanging at the opponent's blue line and waiting to receive a long pass, as part of team strategy.
2. By checking and causing a turnaround in the neutral zone.
3. By beating a man in the neutral zone.
4. By breaking out as a team from its own defensive end.
5. Etc.

In order to decipher this and develop software able to distinguish important differences in variants of something as deceptively simple as crossing the blue line with possession, the developer will likely want to review videos in order to see what was really going on. One might even want a professional hockey coach to distinguish different situations. In the early development stages one would almost certainly want to compare the computer-analyzed data with visual examination of game films in order to ensure that the software is picking up all the important nuances, etc.

So since the developer is going to use video anyway, this approach seems more efficient.

That's a fair point I didn't really consider. There are certainly added benefits to having the video that you don't get from a solely data-driven solution.

[www.theglobeandmail.com]