Michigan Hockey and Corsi: An Experiment

Submitted by Adam Schnepp on October 10th, 2013 at 8:54 AM

Think back to when you started reading mgoblog. Remeber that feeling of validation that there were indeed people out there like you, people who wanted to write about football in way that was funny but also disarmingly analytical? A site that values both memes and knowing the average yards per play for every formation Michigan has run so far this season is my kind of place. It's the reason I've been reading this site since 2006. 

My objective for the coming hockey season is to add something empirical to the mix. I've always gravitated towards advanced stats in hockey, and for those of you who follow college hockey know all too well these types of statistics aren't readily available outside of the NHL. What I'm going to attempt to do is track Michigan's Corsi rating over the entire season. 

Of course, Corsi is just one statistic (even if I'll break it down into a number of different components). The "big idea" behind Corsi is that you have to hold on to the puck to score, and that the team who does a better job of this has a better chance of winning. At the end of the day it provides some interesting insight into puck possession and could be useful for gauging the strength or weakness of special teams play, but it isn't a be-all-end-all stat. There are score effect problems, most notably that even strengh Corsi or Corsi from within one goal in the first and second periods is correlated with winning but it gets dicey in other situations. More on this later.

If you're looking for a nice overview of the statistic you can find that here.

What I need to know from you guys is whether you find it interesting and useful enough to continue tracking. If the fine folks of the MGoCommunity don't like it then I'll go back to writing up goal-by-goal analysis posts like these.

That's cool and all but this post is really boring me. No pictures yet? Come on, do you at least have charts?

Charts? This is mgoblog, fergodsake. Of course I have charts! Let's start by looking at things by period before looking at the bigger picture.

1st Period

  Michigan Waterloo
Goals 0 1
Shots 18 6
Missed 14 5
Blocked 11 4
Total 43 16
% 72.9 27.1

You don't have to know much about Corsi to see that Michigan carried the play in the first period. 72.9% of shot attempts came from the Wolverines, yet Waterloo ended up with the lone first period goal. Michigan made one mistake in defensive coverage in front of their own net and Waterloo took advantage. It's worth noting, however, that Michigan's Corsi total was bolstered by time on the power play (Waterloo didn't have one in the 1st). UM recorded five shots, seven missed shots, and five blocked shots over their two power plays.

2nd Period

  Michigan Waterloo
Goals 1 1
Shots 9 11
Missed 5 4
Blocked 5 5
Total 20 21
% 48.8 51.2

Waterloo seemed to carry play in the second period and the Corsi numbers reflect that. Michigan's goal was something of a fluke, coming after Waterloo's goaltender badly misplayed the puck in front of his own net. Waterloo did get on the power play in the 2nd period, but they failed to register a shot. Their power play generated one missed shot and two blocked shots. Michigan's power play registered three shots, two missed shots, and two blocked shots.

3rd Period

  Michigan Waterloo
Goals 0 0
Shots 10 6
Missed 9 2
Blocked 5 2
Total 24 10
% 70.6 29.4

Here's where the score effect problem I mentioned earlier comes into play. Waterloo was content to carry the puck into the neutral zone and play dump-and-chase in order to burn clock, and when you're playing that style a byproduct is a reduction in the number of shots you take. As you can see, that's certainly reflected in the numbers above. 

Overall

  Michigan Waterloo
Goals 1 2
Shots 37 23
Missed 25 11
Blocked 21 11
Total 84 47
% 64.1 35.9

Michigan had the edge in every category tracked here, yet they couldn't convert opportunities into results. I think that the reason for this lies in the type of shots Michigan was taking; most were from the perimeter, and perimeter shots are much easier for a goaltender to stop than shots through traffic. It will be interesting to see how the possession game plays out against BC, a team with a notoriously stringent defense.

Don't you usually draw on screencaps or something? Why are there all these charts?

Yeah, I call the screencap thing goal-by-goal analysis. I'm not set on moving away from that completely, but I want to know if people find the info above interesting. Like it and I'll keep tracking it, hate it and I'll go back to GBGA.

Comments

truferblue22

October 10th, 2013 at 9:18 AM ^

This is definitely good stuff. A lot of decent information can be obtained from these data sets. I look forward to seeing how it looks after BC shells us tonight. I really appreciate the effort -- hopefully enough of us will feel the same for you to keep it going. Thanks for taking the time to do these!

mgobaran

October 10th, 2013 at 9:50 AM ^

WTF are we? Napoleon Bonaparte? C'mon man!

There is no such thing as a perfect stat, so anything is better than nothing. I have no clue how Corsi is in anyway relevant to hockey, and what the outcome of the game will be. But I am interested in finding out. 

rosedani

October 10th, 2013 at 9:57 AM ^

The more hockey coverage the better!

Corsi seems like a very important stat to follow. One thing I would be more interested in (not sure how feasible/painstaking it is though) is how each line or player performed according to the Corsi rating. It would be fascinating to see if those third and fourth lines really grind in the offense zone or if the top lines are where the quality shots are coming from. Lastly, it would be interesting to see if a certain line's poor Corsi rating is the reason for Red shaking up the lines.

 

Adam Schnepp

October 10th, 2013 at 10:37 AM ^

That's my ultimate goal. I can't even put in to words how much I want to do this, because I think the most interesting information is player-level, but right now I just don't have enough time to do that so I went with team-level data. It's just very time consuming to stop the film every ~40 seconds to write everything down before the next line is rolled out. It's in my long-term plans though, just not sure when.

baconbits

October 10th, 2013 at 8:22 PM ^

I personally would enjoy reading more Corsi takes... like you I'm coming around on Corsi and believe in its worth. Being on the east coast and not able to watch every game, this is a huge help.

MastaDon

October 13th, 2013 at 12:45 PM ^

Total team corsi is good for previewing a matchup, especially in B1G pay when we'll see each team four times. But as a post game recap I find it less useful, it simply says who carried pay which is more or less obvious by watching the game. Player/line corsi is more useful at breaking down who played well or poorly in a particular game, but is obviously more time intensive. GbG stuff is a lot more informative on the technical side.

MastaDon

October 13th, 2013 at 12:47 PM ^

Total team corsi is good for previewing a matchup, especially in B1G pay when we'll see each team four times. But as a post game recap I find it less useful, it simply says who carried pay which is more or less obvious by watching the game. Player/line corsi is more useful at breaking down who played well or poorly in a particular game, but is obviously more time intensive. GbG stuff is a lot more informative on the technical side.