While serving as Buffalo’s goaltending coach in the early 2000s, Jim Corsi sought to devise an accurate barometer for measuring a goalie’s true workload. Reasoning that his netminders had to physically react to a broader range of on-ice stimuli than merely shots on goal, Corsi decided to track missed shot attempts and blocked shots as well.
Little did he realize at the time that his calculation would spark a revolution in the field of hockey analytics. Soon his brainchild served as the basis for a number of puck possession stats, including the Corsi for.
Hockey’s E=MC2 if you will.
Simply put, Corsi for is a team’s total 5-on-5 shot attempts (including missed shots and blocked shots and excluding empty-net shots). Add your team’s totals to your opponents (Corsi against) and divide by the total, and you have your club’s Corsi for %.
Similarly, a player’s individual Corsi is derived from his team’s shot attempts while he’s on the ice versus shot attempts taken by the opposing team. If his Corsi for is above 50%, chances are good that he’s helping his team possess the puck.
Still, strong possession numbers do not guarantee a Stanley Cup, much less a playoff berth. Bubble teams such as Boston, Carolina and Tampa Bay are well ahead of the Penguins in the 2016-17 Corsi rankings. Meanwhile, Chicago, Edmonton and the Rangers all have a Corsi for % below 50 percent.
However, as a general rule, teams that possess the puck experience a greater degree of success than teams that don’t.
Last season the Pens finished fourth in the league with a Corsi for of 53.11%. They’ve slipped a bit this season, currently tied for 12th with Nashville at 50.56%.
Naturally, the downturn is reflected in the Pens’ individual numbers. Only four regulars boast of an improvement in their Corsi. Not surprisingly, the emerging defensive tandem of Ian Cole and Justin Schultz are among the upwardly mobile, along with forwards Matt Cullen and Bryan Rust.
Among the most glaring drop-offs? Defenseman Trevor Daley and forward Phil Kessel.
The primary reason? The Pens are allowing more shots. A lot more.
Last season the black and gold ranked second in shots on goal differential. They averaged 33.2 shots on goal per game—tops in the league—and yielded an average of 29.7 (tied for 15th). This season, they’ve upheld the offensive side of the equation just fine (34.3 shots on goal per game). But they’ve allowed a whopping 32.3, which ranks among the bottom feeders.
Numbers that seem to indicate the Pens are doing more runnin’ and gunnin’ this year, while paying less attention to detail.
Hardly cause for panic, given the locals’ strong performance (fourth in the overall standings). But something Mike Sullivan and his staff surely will focus on down the homestretch.
| Forwards |
Corsi for % |
Defensemen |
Corsi for % |
|||||
| Player | 2016-17 | 2015-16 | Diff | Player | 2016-17 | 2015-16 | Diff | |
| Rowney | 62.5 | — | — | Oleksy | 57.0 | — | — | |
| Hornqvist | 54.8 | 56.8 | -2.0 | Letang | 53.8 | 54.9 | -1.1 | |
| Crosby | 53.2 | 55.1 | -1.9 | Schultz | 52.5 | 50.1 | 1.4 | |
| Malkin | 52.7 | 55.1 | -2.4 | Dumoulin | 51.8 | 53.2 | -1.4 | |
| Hagelin | 52.6 | 57.3 | -4.7 | Cole | 51.3 | 50.1 | 1.2 | |
| Rust | 52.6 | 51.1 | 1.5 | Warsofsky | 50.9 | 57.4 | -6.5 | |
| Kunitz | 52.2 | 56.0 | -3.8 | Maatta | 48.5 | 51.7 | -3.2 | |
| Sheary | 52.0 | 57.5 | -5.5 | Ruhwedel | 47.7 | 41.4* | 6.3 | |
| Wilson | 51.7 | 54.8 | -3.1 | Pouliot | 46.9 | 58.5 | -11.6 | |
| Cullen | 49.6 | 48.6 | 1.0 | Daley | 46.8 | 53.7 | -6.9 | |
| Guentzel | 48.7 | — | — | Gaunce | 46.6 | — | — | |
| Kessel | 47.6 | 54.4 | -6.8 | * With Buffalo | ||||
| Bonino | 47.0 | 51.5 | -4.5 | |||||
| Kuhnhackl | 44.9 | 47.0 | -2.1 | |||||
| Fehr | 42.4 | 48.0 | -5.6 | |||||
| Sestito | 34.5 | 31.3 | 3.2 | |||||
Hey Rick, Hey Jim,
As you guys know, I am a self-professed, stat-geek. I love them. And, since I have been complaining about the Pens giving up way too much zonetime and way too many shots, one may think that I love Corsi stats. Well, truth be told, I neither hate nor love them. I do find them interesting and that is all.
From a team stat perspective, wins and loses matter most, obviously. Of all of the stats, not surprisingly Goal differential and +/- correlate highest to wins, after all the name of the game is to out score not out shoot your opponent. Shots will correlate with goals so in a secondary way, they will affect wins, particularly shot differential. Although I never ran the stats on them, I would think that Corsi would correlate better with +/- than with W% and face-off W% would correlate better with Corsi than with Goals or W%, since it is at best a tertiary stat.
The problem with Corsi is that there are too many confounding variables; Shooting%, Save%, Block Shots, Missed Shots, Perimeter Shots, Slot Shots, Rebound Shots, break away shots, odd man breaks, how much back pressure is on the shooter, Shots by period, shots by score (Leading/Tied/Trailing), 2-dimensional shots (by period by score) it can get dizzying to say the least.
Personally, I look at goal differential and +/- first and second, before any other stat. I know many people try and deride these stats by saying that they are not that reflective off the player but represent all the players on the ice and that is true to some extent. However, regardless of which stat you look at +/-, Corsi, hits, or blocks, most of them are reflective of the whole team effort. Corsi is just as limited as +/- all defenders on the ice get a (+) or (-) when a goal is scored or a shot taken. Even when it comes to goals scored, the only two players that I can remember watching skating through all defending players to get a shot on goal was Bobby Orr and Mario Lemieux.
By the way, way to go Pens, 4-1 W. Hornqvist is in beast mode it appears. But please defenders, you have blown 2 possible shut outs these past 2-wks by lapses late in the game. After all Murray and Fleury have done for you guys you owe them to lock down and get them those shut outs when the opportunity presents itself.
Hi Coach
Well explained.
THANKS.☺
I assume another outside variable is the overall style of play by each team.
Remember the New Jersey Devils of the late 90’s played that defensive trap whereby they slowed the game down….very slow and boring style of hockey to watch and basically tried to win their games with a hot goalie and special teams.Then compare them to a puck posession team that skates like the Pen’s and plays a style whereby you try to score on every shift.
That has to depress the over all Corsi numbers?
What your thoughts Coach?
Am I missing something in my anyalsis. ..
Cheers.
Hey Jim,
100% spot on. A team’s style of play will certainly reflect in their Corsi numbers. A conservative offensive mind set will not lead to a lot of Offensive Zone time which would lead to low Shots For but if that tactic is executed properly the shots for should be quality Shots For. While the Shots Against will tend to be high but mainly low percentage shots
Conversely, aggressive Offenses will get tons of zone time and tons of shots while, if executed properly, limiting their opponents zone time and shots. Their opponents will have lower possession time and there for lower shots. However, aggressive teams will tend to give up more odd man breaks, so higher quality shots. They would tend to lean heavier on their goalie and need a goalie that controls rebounds better. The only thing that may be a higher quality shot than an odd man break shot is a rebound off of an odd man break.
Of course this is why I think the Pens need to move forward with Murray rather than Fleury. I think both are high quality Starters, but Fleury is better suited to a conservative offense. Look at his numbers when MJ was coach. While Murray better suits the Sullivan’s smaller more offensive minded D men.
At least those are my thoughts, take them for what they are worth.
Thanks again for your insight on this Coach.☺
Hi Rick,
The Corsi numbers did in fact bring a new style of coaching to the NHL.Some say that was due to the number of younger, new NHL head and assistant Coaches and new progressive General managers as well. Some of the older guys, or should I properly refer to them as traditionalists find Corsi a bit over rated. As one guy said to me, Corsi does not measure a mans heart !
In my opinion the basic reason our shots against are up over last year, and thus distorts the Corsi ratings is due to 3 or 4 things.
1. Face offs. Defensive and offensive zone. If you can not win the face off there is a good chance you will be playing chase the puck all night.
2. Problems exiting the defensive zone.They have struggled as a team at times during the first 50 games of the season.Even though we had the record winning percentage in December and we are 7 -2 and 1 ??, in the last 10 games, I blame that solely on injuries and call ups. 3. Finding an identity.
I know that sounds strange, but what I mean is because of injuries,people playing in different roles with always changing line mates…that takes time to gel as a group. It will come.Plus some players know that this is their last year as a Pen and that has an effect on team play as well. It has to.
4.The competition has gotten better. A lot better ! For example. Maple leafs. I try not to watch them, but they have 6 or 7 kids on their team and they are fast this year and can they score ! They are going to make the playoffs. Bluejackets are no fluke either. I am not going to name them all, but as we said before there are 12-13 teams playing for 8 spots in the East and everybody wants to beat the Champs. We did not have that last year.
So we need to get healthy, get all our team back and start playing as a group once more and you will see the Corsi numbers improve.
But face offs ??? ……help.
Cheers 🙂
Excellent stuff, guys … 🙂
Hello All!
As I said before, I’m not much for numbers, even though I do monitor some of them when I get the urge (I just don’t tell anyone). I don’t know Corsi from horsey – too complicated – but one of things I’m noticing is they’ve lately had some games where they just look worn out. When I see them relying on blind passes, or just bad passing in general, making questionable decisions, backing up when it’s clear they had a play on the puck, forgetting about puck support and struggling on the boards, I think tired. Eighty-two games is a grind. No one maintains their focus for every one of them. That’s why they have goalies.
Hey 55 on point,
Good point, 82 games is a lot of games, add to that the long play-off run and world cup for some, no doubt some of these guys are worn out. And let’s face it, the Pens are not that big on D and they are taking a pounding.
That is why I have suggested several times that even the stars be healthy scratches, particularly the older ones and against “weaker foes”. They should use those games to give kids some TOI and get their legs going so they are stronger if needed come play-of time.