A Study of Zone Exits (Team Canada WJC 2020 Part 1)

I decided for the World Junior Championships that I would embark on a journey of analytics.  Using a similar formula to what Corey Sznajder has been working with, I tracked Defensive Zone Exit data for Team Canada.  A short version of what this means is:
Whenever Canada made an attempt to move the puck out of their own zone I tracked what happened and how.
This breaks down into 4 event types:
– Exit with possession: The player in question carries the puck out of the zone or completes a pass from the zone to a player outside of it
– Clear: The player pushes the puck out of the zone, but it immediately changes possession.  Icing plays are not counted.
– Failure: The player makes an obvious attempt to get the puck out of the zone and is unsuccessful
– Assist: The player makes a pass to another player in their own zone with the intent of that player moving the puck out and that player successfully executes an “Exit with Possession”

At current time, I have the group stage games completed.
20191226 EER

20191228 EER

20191230 EER

20191231 EER

That’s a lot of data, but what does it all mean?  I further broke down the data into some analytics to help interpret it.
– 5 on 5 Exit Percentage: this is what percentage of the total successful exits at 5 on 5 (even strength) a given player accounted for.  In the example directly above, against the Czech Republic, Ty Smith accounted for 5 of the 48 total 5 on 5 exits with possession.  This calculates out to 10.42%
– Relative Rating: this assumes that each player should be responsible for an equal share of zone exits.  It does not account for situational usage or ice time.  It is based on a baseline mean percentage taken from the number of skaters dressed for a game.  In the NHL this number would be 1/18.  For IIHF games this is 1/20 assuming no injuries.  In games above Canada used 19 and 18 skaters respectively.  Relative rating reflects that.  The number is calculated by taking the “5 on 5 exit percentage” and dividing it by the mean percentage (5.26% for the Canada vs. Czech Republic game shown directly above).  Using Ty Smith again, that means to achieve his relative rating, we would divide is 10.42 exit percentage by 5.26 to get his Relative Rating of 1.98.  By the standard of this metric, that’s a really impressive number.  The short version is: numbers above 1 are good, numbers below 1 not so much.  When we take the Relative Rating and apply it to lineups, we can see what players on each line and defensive pairing are the ones controlling zone exits.
– 5 on 5 EER: EER stands for Exit Efficiency Rating.  This is simply a calculation of a player’s successful zone exits divided by their total number of attempts.  We do not give credit for clearing the puck here, because the  goal is to exit the zone with possession every time.  Using Ty Smith against the Czech Republic again, at 5 on 5, Ty attempted to exit the zone 5 times and was successful every time, giving him a 5on5 EER of 100%.  Looking at Jacob Bernard-Docker in the same game; he attempted to exit the zone a total of 11 times.  He was successful 7 times, he cleared the puck out 3 times and failed completely 1 time.  Therefore his EER is 7/11.  Converting the decimal to percentage and rounding to the nearest hundredth of a percentage point, that number comes to 63.64%

So what’s the point of all this, what does this data tell us?  In part 2 of this installment I will total all the data from the preliminary rounds and try to draw some conclusions from it.

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