by PuckStopsHere on 09/09/09 at 06:25 PM ET
Yesterday, I wrote about the sabermetrics and hockey problem of combining zone starts and Corsi Number. There is as method used by objective NHL that treats Corsi Numbers as a rate statistic and adjusts by a factor similar to the percentage of offensive - defensive zone starts divided by total zone starts. I do not think this is the best method to treat this data.
I take the raw Corsi Number as a starting point. Since each extra offensive zone start is worth on average 0.8 Corsi (or each extra defensive zone start costs on average 0.8 Corsi), I merely add on a factor of 0.8 * (defensive - offensive zone starts). I think this method is more straight forward and better accomplishes the adjustment we are looking for.
Here are the top 20 adjusted Corsi Numbers using this method:
Adj Corsi Number
Rank in Top 20 Corsis
Clearly, the Detroit Red Wings have dominated this list. The top seven on it play for the Wings and an eighth Detroit player is also on the list. This is partially because team effects have not been taken into account (I will do that in a future post) and Detroit has the best Team Corsi Number last season. Detroit is also a team that uses all four lines far more than most teams, thus there are few Detroit players among the top offensive zone starters who will lose the most from their raw Corsi Number as their offensively favorable usage pattern is normalized out.
This list does not significantly change from the top 20 Corsi list. There are four players on this list who did not make that one. They are Eric Staal, Martin Havlat, Curtis Glencross and Sergei Fedorov and all appear near the bottom of this list. Dropped from the raw Corsi list are Nicklas Backstrom, Scott Gomez, Brian Campbell and Jonathan Toews. Each of the dropped players played a more offensive role than the player who replaces him. That more offensive role is the reason for his higher raw Corsi Number. When the effect of his offensive role is removed from the Corsi statistics, he falls relative to the other players.
We see that at the top of the Corsi list, adjusting for zone starts does not make many significant changes. We will soon see if the is also true at the bottom of the Corsi list where there is a stronger correlation between defensive zone starts and poor Corsi Number.
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