Friday, December 30, 2011

Preaching To The Choir - On Why Plus/Minus Is Stupid, Part 38

Plus/Minus is often maligned by fancy stats types as not descriptive - it doesn't take into account the quality of competition or teammates. It doesn't acknowledge whether your team's goaltending is great, horrible, or somewhere in between. There's yet another reason why it's dumb - it describes game states that are not entirely relevant.

Let's take as an example my favorite team, the New Jersey Devils. They are having quite a bizarre season so far - 8-1 in shootouts, their record in regulation is a mere 10-15, but right now they're holding on to a playoff spot. More strange is their special teams play - they've scored a mere 17 power play goals, while allowing a whopping total of 11 short handed goals. Yet while shorthanded, they've only allowed 10 goals and have scored 7 short handed goals themselves. In addition, they've allowed 4 empty net goals and have scored none at even strength. All this has made the team plus minus even more useless than it already is, since as we know, plus/minus includes short handed and empty net goals.

Let's just look at the top 9 forwards' plus minus:

Adam Henrique7
Petr Sykora2
Dainius ZubrusEven
Patrik Elias-4
Zach Parise-5
David Clarkson-10
Ryan Carter-11
Ilya Kovalchuk-12
Mattias Tedenby-14

Looks pretty bad, right? But when we take out short handed goals for and against as well as empty net goals, it looks a lot different:

Forward+/-+/- at ESDifference
Adam Henrique770
Petr Sykora29-7
Dainius ZubrusEven8-8
Patrik Elias-46-10
Zach Parise-52-7
David Clarkson-10-4-6
Ryan Carter-11-10-1
Ilya Kovalchuk-12-1-11
Mattias Tedenby-14-12-2

We see a lot of pluses where there were minuses before. If we were using +/- to talk about even strength play on the Devils, most players have a radically different even strength +/-. We might erroneously think that Ilya Kovalchuk is having a horrible season at even strength, but he's merely been average-ish. What are we even looking to describe when we talk about +/-?

Conclusion: Plus/Minus is stupid. Again.

1 comment:

  1. Well when you have more skaters on the rink for PP and EN, you really shouldn't all of a sudden suck...should you?