One of the great things about the last five to ten years, from my perspective at least, is the relatively new mainstream appeal of being a nerd. I've always been a nerd at heart but I didn't always wear the badge as proudly as I do now and while part of that is a bi-product of growing up, it would probably be dishonest to say that I'd self-identify as one if I were the only person doing it with pride.
In part, I was able to keep my inner-nerd closeted during the time it wasn't so chic because I was reasonably athletic and genuinely loved sports. Given these two interests, it's not particularly surprising that I have a hockey blog.
Being a hockey nerd is a little bit different than liking the Christopher Nolan Batman movies though; it's not exactly universally accepted. Part of that comes from the fact that the advanced stat community often challenges preconceptions that have been held for a very long time in the sport, but part of it comes from misunderstandings. With that in mind, I thought I'd take a little bit of time to clear the air on some of the nerdier elements of hockey analysis.
The Stats We Dislike
(+/-): A lot of advanced statistics is predicated on the idea that "goals" is too narrow a result to be of much predictive value. There aren't enough goals scored to clear up a lot of the statistical noise and a handful of goals against caused by skating with a defensively inept linemate can really skew your own personal results. For this reason hockey nerds tend to seriously dislike (+/-) and this is especially true if you're comparing guys on different teams. (+/-) without regard for context is anathema for us.
Hits: Cam Charron had an exceptional piece over at Backhand Shelf where he touches on how teams with a lot of hits tend to lose a lot of games. The reason behind this is pretty obvious if you actually think about it: In order to make a hit, you can't have the puck which means to make a lot of hits, you have to spend a lot of time without the puck. When a hockey pundit praises a guy for being third in the NHL in hits, you can expect that hockey nerds everywhere are rolling their eyes. To a lesser extent, you can throw out shot blocks for the exact same reason.
Goals Against Average: Goal against might be the most absurd "goalie" stat ever conceived. If there were ever a stat that was screaming to be considered a team statistic rather than an individual one, this might be it. When it comes to goaltending, if you're looking for a regular statistic to use to compare the quality of goaltenders, stick to save percentage.
Why We Like Possession Stats
There are a number of possession stats out there (most being some permutation of corsi or fenwick) and they're all based on getting shots toward the goal and preventing shots from being directed at your goal. The reasons they're based around shots are two-fold. First of all, a shot for or against is only one remove from being a goal and thus can be considered a goal-like event. Since the purpose of hockey is to score more goals than the other team, this makes sense. The second reason is that it provides us with a significantly higher number of events than goals do.
Now the correlations between these possession stats and points in the standings are extraordinarily strong (especially if you isolate for when the game is close) but context is still important here. Is a guy playing against tough opposition? Is a guy getting buried with defensive zone faceoffs? Is he skating with AHLers? Having bad possession numbers, on its own, doesn't mean a guy is necessarily a bad hockey player. It might mean he's mis-cast or it might mean he's given tough assignments.
A Common Error
Perhaps the most common mistake that I encounter with people who are new to advanced stats is that they consider corsi or fenwick to be a measure of a player's defensive aptitude. Both of those metrics are based on both shots for and shots against, and for this reason should be considered a barometer of a player's all-around game.
Why We Fight
The Stats community and the Anti-Stats community seem to get into endless debates about a lot of these things and truthfully, most of the fights I see come from one side reading something that wasn't actually there. Take my statement above as an example: Teams with a lot of hits tend to lose a lot of games. Now someone may infer from that statement that I think hitting is bad or is something to be avoided but that person would be wrong. When you don't have the puck, hitting is one of a small handful of ways to get it back and it's a tool that I absolutely believe in. The reason those teams lose, as I said above, is that they spend too much time without the puck.
Another common argument revolves around luck. The Maple Leafs' shooting percentage with Nazem Kadri on the ice is very high and is almost definitely inflating his point totals. Very few players have seen on-ice shooting percentages as high as his has been most of this year and it's enormously rare for a player to have those numbers stay high year-over-year. What this means is that his point pace, barring further development of his talent, is likely to come down from what it is right now. What it absolutely doesn't mean is that he's a bad player. Just because a hockey nerd says that a player has been lucky, doesn't mean that we think that player is bad, only that he's unlikely to continue the pace at which he's been putting up points.
If you're not really heavily into advanced stats and you're about to engage in a debate with someone who is, read what they're saying very carefully. A lot of times things that may seem counter-intuitive or subversive actually make a lot of sense without needing to delve too deeply into the math.
The best part about writing about hockey is without a doubt the conversations. This outlet has afforded me admission to a community of passionate and insightful individuals who have the same interests that I do, and has given us a forum to debate our ideas. Twitter has been the source of no end of great hockey conversations for me and I love having those discussions, even when we disagree.
The more we understand each other, the better conversations we can have and that's a two-way street. If you don't understand why someone has the opinion they do about a certain player or team or situation then ask and, when they answer, listen carefully. If I can understand you and you can understand me, we're probably both going to learn a thing or two.