Ogopogo*
Guest
The purpose of corsi, from my understanding, is that it is an approximation for possession. Within that there is value. Obviously it is not a 100% accurate in any circumstance, however it tends to give us a larger sample size than strictly shots on goal while also seeming to be fairly accurate with regards to both good and bad players. It accurately assesses the lack of value a guy like Luke Gazdic has, while demonstrating the value of having an Anze Kopitar.
If Team A shoots 40 times but only 24 hit the net, while Team B hits the net with all 4 of their shots they'll be given the same shot total but who would you assume had possession of the puck more often? At a team level, that's all corsi really is. At an individual level I can see the flaws that it may have, but it still works in the same way. Yes, there are 10 players on the ice but certain players are obviously gonna be better at helping move the puck in a positive direction.
Also i'm not sure what you meant by "nobody takes the time to measure individual contributions".
Corsi doesn't measure possession, it measures shot attempts - those are two different things. I see it as arrogance from the Corsi community to even refer to their flawed numbers as possession numbers. Possession can be measured in several ways, but shot attempts is not one of them. Possession can be time of possession or even number of touches.
If Kopitar played with Gazdic on his wing all season long - every time one of them is on the ice the other is as well - what do you say then? Kopitar and Gazdic both have the same Corsi - who is good? Who is not? That is the problem with Corsi - put a bum out with good players and his Corsi is good. Put a good player out with bums and his Corsi suffers - it is NOT an individual measure no matter how much the cult wants to believe it. Corsi is a guess at best. It would be like saying that the murder rate in Edmonton has dropped since I moved here so I have a good Corsi for murder rates. Really? Is that all on me? I am a small part of the whole - it makes no sense to pin it on me. The concept is the same with 12 players on the ice as it is with 1.2 million people in the metro Edmonton area. You cannot pin a group stat on an individual - it is completely inaccurate and little more than a guess.
When I say "nobody takes the time to measure individual contributions" I mean nobody measures what individuals do on the ice. We can all see when players make mistakes - whether they lead to shots, goals or lead to nothing at all. We can also see when players make a particularly good play - something above average so to speak. Those may lead to goals, shot attempts or nothing as well. If we were to accumulate all of the + marks for a good play and subtract all of the - marks for a poor play for each individual then we would have some real individual measurement. It would be very easy to see individual contributions or lack thereof for each player in the NHL. But, instead, people would rather use the lazy man's Corsi and have numbers that really don't mean anything because they are team stats.
The entire point of "advanced stats" is to provide insight. The idea of "Moneyball" is what people are trying to replicate for hockey and they are doing it completely wrong. Would it make any sense at all to calculate the number of hits against a team and blame that on the 3rd baseman - like Corsi does? Absolutely not. What about the hits for a team and credit that to the same 3rd baseman? Is it really all on him? Nope.
Baseball is wonderful in that, it is easy to measure accomplishments of the hitters because hitting is an individual act within a team concept. If I hit, you can measure it. If I strike out, you can measure it. All of that is completely on me. In hockey, aside from goals and assists, there really aren't any other numbers that you can credit an individual for. Corsi is a very weak attempt to pin an all-around performance measure on an individual - it is like giving a 3rd baseman a score for the teams hits for and against. To measure true individual performance you have to watch the game, hockey is a sport where you cannot quantify an all around performer with a ridiculous team stat like Corsi. A true +/- of actual individual play where a player gets credit for good plays and debited for gaffes is the way to do it. Corsi will never be the answer - the number is influenced far too greatly by the other 11 players on the ice. My idea isolates an individual and measures them on their performance alone - that is what the entire point of advanced analytics is. Find the undervalued players with better ways to measure - not confuse the world with crap like Corsi.
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