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02-04-2013, 06:50 PM
  #101
WarriorOfGandhi
Was saying Boo-urns
 
Join Date: Jul 2007
Location: Cincinnati, Ohio
Country: Scotland
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Quote:
Originally Posted by The Mars Volchenkov View Post
Someone should try to explain this Corsi stuff to me because whenever I look at it I just don't know what I'm looking at. Maybe I'm not looking hard enough. Or I'm an idiot. The shots for/against is easy enough.
Quote:
Originally Posted by bohlmeister View Post
It appears as though they take your shots for and subtract the shots against, and that is your Corsi. So if you are out there and the team gets more shots against than you do for, it is assumed by some that you are an inferior defender. Zone starts and quality of competition are needed to really make it useful. All these stats are good for people that don't watch the games or want to prove to other people that their opinion is right. Hmmmm, maybe I should start using advanced stats to back my arguments.......
Quote:
Originally Posted by Freudian View Post
Corsi basically is just that. Shots for and shots against when you're on the ice. It's supposed to signify puck possession but it's quite flawed for many reasons.

First is obviously zone starts. O'Byrne and Zanon start most of their shifts in the defensive zone. That leads to shots against.

Secondly, we have no way of valuing quality of shots. Part of the reason Landeskog is a Corsi god is that he takes a lot of low percentage shots. I don't mind him doing that, but quite a few of them are shots just to go on a line change. Compare with Eberle who only shoots when he's in close in a good spot. His shots are 'worth' more Landeskog shots, since they have a completely different approach to shooting.

On one level Corsi/zone starts and all these things are interesting but they aren't the Rosetta Stone of hockey, unlocking a perfect understanding of the game. Sadly many followers of advanced hockey stats lack a basic understanding of how stats work so they tend to get carried away with them.

I like stats, but I think watching games tells you much more about teams and players. You never get context when just looking at stats.

/rant over.
Quote:
Originally Posted by Avs71 View Post
This description is exactly why I hate it. Every single EJ thread turns into "he faces weak competition and is a 2nd pairing defender. This is a fact. I don't need to watch games because Corsi tells me." Guys like Eskimo and EvaUnitZero or whatever his name is live off it.

I never post advanced statistics, but I just posted what that guy had in the article because it was actually praising a Hunwick-EJ pairing, which is oddly surprising.
because Corsi encompasses blocked shots as well as shots that miss the net it can determine the balance of attempted scoring chances for and against whenever a player is on ice. The goal of every skater on the ice, whether its Crosby or Koci, is to create goals, and the only way to create goals is to take shots. It's valuable for an understanding of the flow of the game. Guys like Malkin post positive Corsi stats year after year while guys like Bolland who take the toughest minutes in the league get hammered. That doesn't mean Bolland is worse defensively than Malkin but it means that when Bolland is on the ice, it is more likely his team gives up a goal than scores it, a result of both his skills and his circumstance.

Like others said, you have to use zone starts and quality of competition to get an understanding of what Corsi means. Elliott posted the best Corsi on the Avs last season, but it was just as much an indication of his skill as it was the fact that he started 70% of his shifts in the offensive zone and rarely played against impact NHL players. As suggested above, any stat by itself doesn't mean much. A good Corsi doesn't indicate a good defensive player any more than Cheechoo's 56 goals indicated he was the best scorer in the game or Preissing at +40 indicated he was a non-pillow-soft player.

I don't think anyone would argue that watching players is the best way to determine their defensive (and offensive) value. Since that's impossible and subject players to human bias, however, advanced stats offer a lot of insight that the box score cannot.

If you have about an hour to read through it, I strongly recommend reading the entirety of this:
http://hockeyanalytics.com/2012/06/2...-usage-charts/

It outlines the value of Corsi when used in tandem with zone starts and quality of competition and goes through each team and each player. I've gone back to look at it quite frequently whenever I want a breakdown of how a player did last year. Their observations on the Avs are quite interesting. Anyone who was upset with McClement not being offered a better contract should take a gander. Their take on our boy Mitchell is also really interesting. And yes, it does suggest that EJ had only an "ok" year last season -- which I'd agree with without reading any statistical breakdown.

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