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07-12-2012, 03:26 PM
Czech Your Math
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Originally Posted by overpass View Post
This would be mostly because of the players they play with and the players they play against, correct? Brian MacDonald has calculated fully adjusted plus-minus numbers that account for these factors, but they only cover the last few seasons because they necessary data only exists for those seasons.

Just looking at the data it appears that having 2 or 3 star players together on a line is a big factor in plus-minus, including basic adjusted versions. See Trottier/Bossy, Simmer/Dionne/Taylor, Gretzky/Kurri, Savard/Larmer, Leclair/Lindros, Kariya/Selanne, Heatley/Spezza/Alfredsson, etc. Compare to players like younger Steve Yzerman or Dale Hawerchuk who didn't have star linemates and didn't stand out in plus-minus. Marcel Dionne was only OK in plus-minus in his first few seasons, but when Dave Taylor and later Charlie Simmer joined him they were dominant in plus-minus.

If you want to move beyond a "basic" adjusted plus-minus and start adjusting for teammates, by all means go for it. I haven't done so because the data isn't easily available and I don't want to put the time into merging databases (one of those time-consuming tasks that is often required). But it might be possible to adjust historical (pre-lockout) data for the effect of linemates to some degree by using the number of even strength points players participated in together as a proxy for time spent together.
As you point out, except for very recently, there just doesn't seem to be enough data for which teammates were on the ice together at ES, nor for which opponents they faced at ES.

I think plusandminus mentions one factor that might possibly be used to refine adjusted plus-minus further, which is to divide the ESGF portion more in proportion to ES points/ESGF for each player. The ESGA portion has less optimal options. Does one somehow reduce the ESGA attribution for forwards (which are generally focused more on ESGF) and increase it for d-men? I think to do so fairly would be difficult without the appropriate data.

I really like the elegant simplicity of adjusted plus-minus, as I've said in previous posts. Adding more components could yield an even better metric, but one would have to be confident that the new attributions were fair and consistent for both forwards and d-men, which seems difficult to achieve while retaining similar understanding and acceptance of the current metric, esp. given the limits of the data as you go farther back pre-lockout.

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