(Ed. Note: Kent Wilson it the managing editor for Flames Nation, who has written for Hockey Prospectus and Houses of the Hockey. We're honored to bring his intelligent and thorough analysis of the NHL to you here on Puck Daddy.)
"Whatever you think you know about your team's supposed ability to maintain high shooting and save percentages, they are very likely to crash back to league average regardless of how many shots you've observed. Internalize this…and you can make a lot of money betting against people who are convinced there's mysticism in scoring goals." - Gabriel Desjardins, Why You Should Ignore Shooting Percentage
Unless you are a Minnesota Wild fan or a numbers-inclined hockey analyst, you're probably only vaguely aware of the on-going battle between these two factions. Here is some background on the matter:
After the first 31 games of the season, Minnesota was leading the Western Conference in points. Their Cinderella-like rise from the West's basement was an apparent confirmation of the organization's various off-season moves, from hiring bench boss Mike Yeo, to dealing Brent Burns and Martin Havlat for Dany Heatley and Devin Setoguchi. A Church of Yeo sprung up in worship of the new bench bosses uncanny ability to squeeze success out of a line-up that was predicted by most to miss the playoffs.
Minnesota's record was unlikely for a numbers of reasons. Not the least of which was the fact they were getting routinely outshot. In fact, despite boasting one of the best records in the league at the time, the Wild had surrendered 173 more shots on net at even strength than they had generated up to that point. They had also blocked 145 more shots than the opposition. Again, that's only at even strength.
Their total shots for/against (or "CORSI ratio") to that point was just .419, one of the worst in the league. Nevertheless, the underdog Wild were "finding ways to win," to borrow a cliché, so any skepticism was dismissed out of hand.
After all, pointing to the standings could readily silence any unbeliever.
There were some persistent heretics, however — statistically oriented writers and bloggers who acknowledged the Wild were living off of sky-high save percentages that were unlikely to continue in perpetuity. Truly great teams, it was argued, tend to control puck possession and outshoot their opponents. As such, Minnesota's success was likely a mirage. Regression was inevitable and with it, a fall from grace.
Raining on a parade is never popular. The Minnesota faithful understandably bristled at suggestions their team was merely lucky.
"Regression to the mean" became a punch line in Wild fan circles.
Of course, with Minny currently sitting 12th in the Western Conference heading into Thursday night, the next chapter of this story is an obvious one. Daniel Wagner of Backhand Shelf summarizes here what has happened since.
The purpose of this article isn't to dance on the grave of the Wild's short-lived elite status. Nor is it to point and laugh at Wild fans. The episode is an object lesson in how percentages can vary wildly around a mean in small samples and why that is so counter-intuitive to the fan experience.
Read More »from The ‘Stats Guys’ vs. Cinderella, or how Minnesota Wild regressed to the mean