Advanced Stats: Understanding the Need for context. Case Study: Douglas Murray

Reader Zach Fabi, a second semester senior at the US Military Academy at West Point, majoring in Engineering Management (Systems Engineering) came to us willing to explain some advanced stats. Over the past two years he has done significant work with statistical analysis, primarily analyzing baseball statistics, done two internships over the past two summers with the New York Yankees working in their scouting department running regressions and analysis for their minor league system.

Today Zach looks at what the advanced stats tell us about Douglas Murray.

Understanding the Need for Context When Using Statistics

 Last week the Pittsburgh Penguins traded for everyone’s favorite Coke machine on skates when they gave up a 2nd rounder and a conditional 2nd rounder for Douglas Murray.

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Almost immediately people across the hockey world who don’t happen to root for the guys in Black and Gold (feel free to include Bruins fans in this group as well) began to bash the Penguins for the move.

They said he was slow, a sloppy skater who was even more sloppy with the puck. They said he was past his prime, and was not worth two draft picks, especially picks as high as 2 second rounders.

They then began to site his peripherals and advanced stats as reasons why he was a bad addition to a Pens team that was flying high. They looked at his Corsi, and his Quality of Competition and said that he is easily one of the worst defensemen in the league (I’m not quite the twitter fiend the rest of the Pensblog staff is so I’m not going to go digging through the archives to prove my point).

There was a fanpost over on another Penguins blog, Pensburgh, that attempted to give context to the Murray deal by using advanced stats  .

He does a pretty good job of explaining why Murray’s peripherals are fairly sub-par, but I think he misses the boat slightly here. The reality of the matter is, statistics only take you so far when it comes to explaining the context of a situation. True, Murray doesn’t have great peripherals, and a lot of this can be attributed to small sample size this year, and the poor quality of his teammates, but none of this means that he will not be able to contribute to this Penguins team in a big way.

The Penguins acquired Douglas Murray with a certain expectation. That expectation was that Murray would provide a (quite) large physical presence on the blue line, one that would give up the body, block shots, and clear the crease. He is a defensive defenseman, not someone who is expected to provide much in terms of possession or goal scoring (as if that longest active goal-less streak wasn’t a dead giveaway).

Many people will say, ok, that’s great, he’s a defensive defenseman, but that doesn’t mean he should have shoddy peripheral statistics. Well, actually, let’s take a look at the numbers. I did some (very poor) detective work and went searching for the guys who are considered the best of the so-called “defensive defensemen.” Admittedly this detective work involved a single google search, but it lead me to a Bleacher Report article from last year, where they made a nice little slide show list of the top ten defensive defensemen in the NHL.  I then took those defensemen, added Douglas Murray to the list, and compiled some of their stats from behindthenet.ca and NHL.com, and I made another table

 

Figure 1 (Top Ten Defensive Defensemen)

Murray who owns a -10.5 Corsi On beats only one from the top 10, and that is Ladislav Smid (-12.06) of the Edmonton Oilers.
What this means is, if Murray was on the ice for all 60 minutes of a specific Penguins game, the Pens would give up 10.5 more shots per game than the opposing team. But if you look at the rest of the top 10, which as you might have noticed includes Brooks Orpik, only 5 of them posted a Corsi On above 0. Some of this might be explained by the percentage of the time each player starts in the offensive zone.
Of the 5 players who posted a positive Corsi, 2 of them start in the offensive zone more than 50 percent of the time. 
The other 3 include:
– Zdeno Chara, who is known for having one of the hardest shots in the league.
– Dennis Seidenberg, who also plays on the Bruins who are one of the top teams in the league.
– Dan Girardi, who is less than one shot over 0.
 
Some of these numbers may also be attributed to the quality of the competition these guys were facing. Again, Murray ranks second to the bottom of the list, with a Corsi Relative to Quality of Competition of -.263, only beating out Mark Stuart of the Winnipeg Jets at -.284. This really shouldn’t bother us too much however, as I stated, Murray wasn’t brought here to be a part of the top defensive pairing, so he won’t be facing big minutes against the top lines of the teams the Pens are playing.
 Now we can look at some of the “boring normal stats” that have been around for while, Blocked Shots and Hits, or two of the main things that Murray was brought in to do for the Pens.
In the top ten, Murray ranks ahead of 4 in blocked shots with 67, and ahead of 3 of them for hits with 63.
 
Those are really the only numbers that matter, Murray isn’t the best puck moving defenseman, and he’s not going to be facing the best lines that the Penguins will be up against, but he is going to block shots at a pace that is better than or on par with some of the best defensive defensemen in the league, and he is going to punish opposing players who enter the Penguins zone just as well.
 
I am not saying that Murray is the best D-man the Pens could have picked up, and I’m not saying it was a great move or a bad one, but I will say that to criticize the move on the basis of advanced statistics is a flawed approach. Murray will do exactly what Shero brought him in to do, block shots and hit people, and he will do it well.
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