Controlled Situation Corsi: Shawn Thornton and the Boston Bruins

ShawnThornton

More arguments over the role of character in team sports have been waged than Simpsons episodes watched this past week. Well, maybe not. But every day it seems, a main stream media member churns out a piece on the value that a fourth liner brings to an organization, one supposedly well beyond their pay grade and ice time. Inevitably, bloggers and analysts shoot back about the lack of correlation between toughness and victory, or the impossibility of measuring something like leadership in the grand scheme of the game.

The truth of the matter is that neither side of the argument, in its purest form, is wrong. I’ve played enough team sports in my life to know that the presence of guys with positive, influential, and commanding voices can lead to better teamwork, to pushing that little bit harder, and to look on the bright side when times are tough. On the flip side, that difference is nearly impossible to measure, and therefore sacrificing talent for character — from a management perspective — or painting a role player as a star contributor — from a media point of view — isn’t justifiable.

I can understand the instinct to support good people because I’ve experienced it. Having the good fortune to work for the Capitals the past two seasons, I’ve interacted with a number of players, and some stand out as the real nice guys of the sport (at some point I’ll write about my awkward confrontation with the awesome Adam Burish).

But maybe the nicest of the bunch was a 6’2”, 217 lb enforcer named Shawn Thornton. As somebody who prides myself on objective, thorough analysis no matter the team, I’ve had to resist blurring the line between supporting a good man and having that skew my writing. A Thornton or Burish being a great individual does not make them inherently good hockey players. As Houston Astros GM Jeff Luhnow once said, “there is no correlation between being a nice guy or a good person and being a good baseball player.” The same applies to hockey.

Thornton has been a catalyst for debate over the past season, both because he is one of the last of the dying enforcer breed, and because he is generally seen to be an “important fourth liner” playing on the “best fourth line in the league”.

Joe Haggerty recently wrote this article about the outgoing Bruin Thornton, now of the Florida Panthers, and it sounded like a media member who will sorely miss a departing friend who clearly had an impact on the mental state of his teammates. There’s nothing wrong with that, either morally or factually, but in order to examine whether Thornton was also important to the team’s success on the ice, one needs to examine the question with a higher level of scrutiny.

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A few months ago, before being poached away by the Oilers, blogger Tyler Dellow delved into the world of controlled situation corsi percentage. He found that after a certain number of seconds, the effect of a faceoff’s zone location and result is neutralized, leading to what he termed “open play corsi”, or rather corsi devoid of faceoff bias. This summer, figuring that Dellow might not be in the public eye much longer, I sought to replicate his work with the idea of expanding on it.

I haven’t tested for the repeatability of his findings, or their correlation to winning. That is work that I hope to do in the near future, but for now, this is a taste.

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In analyzing Thornton, I decided to examine his performance following offensive zone faceoff losses for a few reasons. First off, enforcers are often given these minutes because coaches feel they need to be “sheltered”. The upside to sheltering fourth liners is that it’s less likely the players immediately get trapped in their own zone and/or scored upon. The opportunity cost, however, is that the team’s stars can’t take on these assignments and begin their shifts with direct opportunities to score. Second, despite the Bruins being a top possession team for the past number of years, they have traditionally ranked fairly low following offensive zone faceoff losses. This, of course, is only the fourth line’s fault to a small extent, but the gap was notable enough to investigate.

The final reason I chose offensive zone faceoff losses (or more strictly, the shot attempt differential in the subsequent 21 seconds) is because they require wingers like Thornton to exert forecheck pressure. Centers and defensemen generally are less important at keeping the puck in the zone than their wing counterparts in these situations. Here are Thornton’s numbers from the past two full seasons (considering the small sample sizes I felt using 2012-13 would be even less reliable) compared to some of the other prominent fourth liners from top teams. I’m not so sure “best fourth line in the league” was really an accurate claim.

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Dellow’s research with regards to the Oilers uncovered tactical decision-making that led to suboptimal outcomes. I watched Thornton’s first 10 and last 10 on-ice offensive zone faceoff losses from the 2013-14 season to see whether I felt that his poor results were tactical or technical in nature. In the end, the answer seemed pretty clear cut. At least in this small sample, it seemed as though Thornton’s lack of speed and inability to win board battles despite his size was a hindrance to his line in offensive zone situations. Take a look for yourself, I paused the video at moments where I felt that Thornton was at least partially responsible for the puck exiting the opposition’s zone.

Acquiring character players can give a team a psychological edge, but assigning causality based on that with the type of primitive analytics we have at our disposal means risking massive mistakes. Thornton is a great guy, and by all accounts a fantastic teammate and leader, but if a restructured fourth line means improved play in sheltered minutes, than Thornton might not be missed on the ice as much as he will be off it.

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