I don't trust the positions that the NHL provides. Wingers are often labeled as centers, and that can make certain types of analysis hard to do. So to figure out who's actually playing in the middle, I look at the faceoffs: Players who take the majority of the draws while they're on the ice are listed as C's, and those who aren't are listed as wingers.
More centers come into the league then there are spots available for them. This is because the best forwards are frequently playing as centers when they are the dominant player on their team. So pre-season is the time to talk about position swapping. As players with some good NHL performances under their belt start rattling the cages of moving to most forward's preferred spot on the ice: down the middle, I was interested in how these players who do transition from winger to center perform.
I used Progressive Hockey's own Rel. Exp GF% to compare their season at their new position to how they did the previous year. I'm using it because:
a) Takes care of possible variance in usage (teammates, competition, zone starts and score state)
b) Weighting fenwick shot differential by a shot quality model means I don't have to do too much extra thinking about parts of their production I might be excluding.
I found 103 cases since 2008 of wingers converting to center. Here's how they did.
Converted wingers on average saw a -1.9% decrease in their Rel. Exp GF% in their first season at center. They fared slightly better in their second season at the position, only seeing a 1.5% from their last season at winger, but did even worse in their third season if they stuck with it, with a 2.1% decrease from their last season at wing in a decreasing sample size (55). Converted wingers who had a Relative Exp. GF% above 0 (average) the previous season saw a 5% decline during their subsequent season at center .
Conversely, centers transitioning to wingers have gotten a bump in their production.
Remember that Rel. Exp GF% is adjusting for things like the strength of the line and zone starts, so this is as close to a pure indication of performance as one can get.
What is proven here is actually somewhat straight forward: Center is a tough job with added responsibilities, and the majority of wingers who make the jump see a somewhat drastic drop in their performance. Notable exceptions include Nazem Kadri, Maxime Talbot and Claude Giroux.
The first reaction to this evidence is to think that teams are trying too hard to turn their wingers into
centers, but one should consider the defensive scale in baseball.
There's a range of difficulty to each position in baseball, and so if any player moves up or down a position (in terms of difficulty) he would theoretically see a boost or hit to his performance at that position. But because of this his competence is not intrinsically tied to his value. A bad shortstop is still more valuable then an excellent fielding first baseman.
I think we could make the following conclusions:
1) Very few players who make the transition from winger to center are not going to see a decline in their production. 63% of them get worse, and that is cast in a more negative light by the fact the average age of these players a point where they should be seeing their most rapid improvements.
2) Production, in the way I'm using it, is not the same as value. As center is a more valuable position, there is more scarcity of elite center talent, so one would be willing to accept a certain loss of production based on one's own particular roster needs.
I think this is a first step to figuring out some basic economic tenants of the hockey market place. Teams have been willing to give up a better winger for a slightly worse center, and that is, at the very least, objective evidence to something most analysts have known all along.