[tknez16]

Here's a little rant I prepped about advanced stats. I thought about a new thread, but this fits nicely here.

People greatly misunderstand “advanced stats” for hockey. This derives, mostly, from wanting to simplify what they mean. “Is this team/player good?” is not a question that’s answered by the current stats that are being tracked. Generally, they track something more specific. Here are the two that really bother me in how they’re interpreted.

PDO (Shooting % + Save %) – This isn’t a great stat, but it’s the only one that really says “Is this team playing well?” If you have a high shooting percentage and a high save percentage, then you’ll win lots… and that’s obviously not a coincidence.

What this isn’t, is a proxy for luck. Sure, a team that’s lucky will have a higher PDO, but this also reflects skill, both offensive and defensive. If a team has a very high PDO, then it could be either luck or skill (if it’s high enough, then likely both) that cause it. For the Flames, many pundits will say it’s all luck because the story lines going into the season said that the team would be bad. This take is simply bias, just as all of us Flames fans hating their take is our own bias. Media types don’t want to admit they were wrong about the skill level of the team, while fans will tend to overrate their team’s skill level.

Corsi (Shot Attempt Differential) – The biggest thing that bothers me about this stat is how it’s interpreted. This does not say whether a player/team is good. It says how much a player/team controls the puck. Generally speaking, teams that control the puck more tend to be better. This is not a rule. Different styles of play will greatly affect corsi ratings.

The misconception that corsi directly relates to team quality comes from the trend in play style in the league. Most teams play a puck possession game. If you play a game that’s centered on puck possession and you have a bad corsi, chances are that you’re a bad team because you aren’t achieving your goal of controlling the puck.

On the other hand, there are teams that don’t play a puck possession game, but instead concentrate on hard puck pursuit and collapse in the defensive zone. We Flames fans are familiar with this. When a team collapses in the defensive zone and concentrates more on shot blocking, it tends to control the puck less and have more shot attempts against. When a team doesn’t have large amounts of offensive zone time, instead scoring on the rush and on turnovers, they will not have a large number of shot attempts for. When both of those are the same team, they will have a terrible corsi. This has nothing to do with them being a bad team, but simply their style of play.

Tl;dr – Advanced stats aren’t bad, they’re just misused.