Recently I witnessed a discussion in which two people were arguing whether or not Luke Schenn had a good season. Broad Street Hockey had a great article breaking down his season recently. The individual who was stating that he had a poor season was arguing that his high number of hits mean next to nothing (perhaps true), and that his plus-minus was poor; therefore he is not a good defenseman. That is funny in itself because Schenn was a plus-three, good for third on the team in plus-minus among players playing 10 or more games, and second among defenseman. The Flyers leader was only a plus-eight. I’m not even sure how this person came to their conclusion, but I digress.
The fact that people so frequently point to plus-minus as a means of gauging an individual player really frustrates me. Without any context, the stat is almost useless. With context, it isn’t entirely useless.
How was his team’s goal differential as a whole? What quality of teammates did he play with? What quality of opponents did he play against? Did he usually start his shifts in the offensive or defensive zone?
If you play on the Florida Panthers (worst goal differential in the league), with a partner that is the equivalent of someone like Andreas Lilja or Kurtis Foster, playing against Sidney Crosby constantly, and you’re starting in your own defensive zone 70% of the time…I’m willing to bet you’re going to be a minus player. Even if you’re the best player in the world.
If you play on the Chicago Blackhawks (best goal differential in the league), with a partner that is the equivalent of someone like Erik Karlsson or PK Subban, playing against Jody Shelley constantly, and you’re starting in the offensive zone 70% of the time…I’m willing to bet you’re going to be a plus player. Even if you’re…well…you (I’m assuming whoever is reading this is not an NHL player).
As an experiment of sorts, I reached out to a friend of mine, Jason. He is not a sports fan in the slightest, and was a philosophy major in college. I thought he’d be an interesting subject to discuss plus-minus with.
Here is a transcript of our conversation:
Me: Plus-minus is a stat that measures the difference beteween goals scored for you versus against you, while you’re on the ice. If you are on the ice and your team scores, you get a plus. If you are on the ice and you get scored on, you get a minus.
Jason: That’s a weird statistic…but go on…
Me: If you were on a really bad team, would you think you are likely to be a plus-player or a minus-player?
Jason: You would be a minus-player despite the fact that some of it is out of your control. That stat seems like it’s not going to be really helpful in describing anything.
Me: I would agree with you.
Jason: That’s a really dumb way to gauge an individual. It should be revamped to reflect a line of players. That’s what five players are called when they’re on the ice together right? A line?
Me: I think I might actually publish our conversation.
Jason: Can you just spell check it for me? And you can publish that as well.
In true philosopher fashion, he then went on a bit of a diatribe about statistics and sports that is sure to please the advanced statistics crowd.
Jason: I think that everyone that likes sports should read books on statistics.
Me: Man, you are making me so happy right now.
Jason: It’s just, if you really like sports, and you like talking about it…you need to understand the math behind the statistics you talk about. If you’re into sports, and you’re an adult, that means you’re into math.
All major sports come down to math and anyone living the age of information that doesn’t get that will be left behind.
I personally agree with Jason. I’m a numbers guy, but the dichotomy between the statistics lovers and the traditionalists I always found to be too extreme. I find it silly to complete dismiss stats. I find it equally silly to ignore what you see. However, your eyes can lie to you. I prefer to use statistics to support something I see. Or, if something really jumps out to me in some statistic, it will prompt me to watch more closely to see what I might possibly be missing.
With that, I’d like to leave you with one of my favorite articles regarding advanced statistics in hockey. James Mirtle wrote about how the Penguins used advanced analytics before they decided to trade for James Neal. They now don’t make any major decisions without consulting their statisticians.