Friday, February 22, 2013

Explaining Advanced Hockey Statistics in a Nutshell: The Corsi Number

By Finesse

After doing a post two days ago about how Ovechkin's current decline is not as much like the supposed decline of the true all-time great players as some want to make you believe, we were chastised by that author because in his mind, we hadn't sufficiently "read up on Corsi and Fenwick."  Unlike him, we're comfortable looking in the mirror and questioning ourselves.  So we spent a good deal of yesterday "reading up on" Corsi.  Here's what we learned.

The Corsi number was created in the last decade by Buffalo Sabres goalie coach Jim Corsi, so it must be good.  Basically, the Corsi number measures a player's plus/minus for shots attempted.  So if you're one of those people who thinks that regular plus/minus is of limited utility, you'll love the Corsi number because it factors out scoring goals and factors in getting your shot blocked. [Cut to Tyler Kennedy nodding approvingly].

A player's Corsi number is the difference between the shots attempted by a player's team and the shots attempted against a player's team (while that player is on the ice).  A "shot attempted" includes shots that hit the net, miss the net, or are blocked.  This is the formula:

Corsi Number = (Shots on Target For + Missed Shots For + Blocked Shots Against ) - (Shots on Target Against + Missed Shots Against + Blocked Shots For)

The Corsi number factors out goaltending.  How convenient for Buffalo. 
Still confused?  Here's how you know Corsi is a good statistic.  Because Sidney Crosby is ranked 65th. Thomas Vanek is ranked 273rd. Steven Stamkos is ranked 362nd. John Tavares is ranked 152nd. Patrick Kane is ranked 626th.  Henrick Zetterberg is ranked 220th.  Martin St. Louis is ranked 484th.  Patrick Elias is ranked 45th. Evgeni Malkin is ranked 64th. Matt Moulson is ranked 170th.

In the outdated statistic of points, those ten are ranked 1st through 10th.

Still not convinced about Corsi's utility?  Here's a video from last night's Wings-Blue Jackets game that really encapsulates the Corsi point.  Number 24 on the Red Wings likely got a Corsi point for indiscriminately shooting puck toward the net and having it blocked, which immediately led to Columbus's game winning goal.

As for the Fenwick statistic, we'll get back to you on that.  All we can tell you at this point is that if Corsi and Fenwick were defensemen, Mario would have split them.

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