ZHR is back, with a much larger sample size. This time, I've included each team's first twenty games.
As I explained in my earlier post, ZHR is an attempt to isolate defensive work done by a team. Basically, it counts all of the hits given and taken in a team's defensive end, and divides that number by all the hits given and taken in the team's offensive end to come up with a ratio.
Results after the jump.
Some teams hit and are hit much more frequently in one zone over the other, and I am tracking this as an indication of game flow. This is why the average ZHR is not 1, but instead is 1.011.
The standard deviation is 0.13, so once again, no two teams are more or less than 2 standard deviations above or below the mean.
The logic behind ZHR is that since hits can only be administered to the puck carrier, each hit can be counted as a contestation for the puck. If there are more of these contestations happening in your end than in your opponents', your defense must be under greater pressure, since they are being relied upon to recover puck possession.
It should be noted that since ZHR is a ratio, teams that simply hit more frequently will not be recognized as having done more work. ZHR simply looks for disparity between work done in the offensive and defensive zones. For this reason, I've included the average number of hits per game by each team (see below).
To bring the focus onto the Leafs, I find it surprising that their ZHR actually sits at 0.971, which is below the average mark of 1.011. Much in the same way that Corsi or Fenwick numbers can look good when a team is constantly trailing, I would speculate that the number of offensive zone hits may be rising when a team is trailing as well. I have noticed that a team on the winning side of a blowout is often out-hit, but this is by no means a surefire explanation for this phenomenon. ZHR shows no meaningful relationship to where a given team sits in the standings, and if winning teams were to be out-hit on a regular basis, one would expect such a trend to show itself there.
What we can glean from this is the Leafs are relying slightly more on their forwards for puck recovery than their defense, and that this has, so far, been a failing strategy. It's interesting that the Canadiens, with the smallest forwards in the league, have managed to hit about equally in both ends, and are nevertheless winning games.
The Leafs' "D" may not actually be under as much pressure as that of most losing teams. I think that it is worthwhile to note that currently, the Leafs sit 10th overall in blocked shots, and 10th overall in ZHR. Admittedly, the shot-blocking stats I'm looking at are from the morning of December 1st, and so include more than the 20 games I've used for the ZHR study, but they may still provide some kind of interesting connection that I'll keep my eye on throughout the season. What seems to really be killing this team is Giveaways, a category in which they currently lead the league.
