The other day over at PensionPlanPuppets.com there was a post by Draglikepull looking at zone exits by Maple Leaf defensemen for the first half of last season. If you haven’t seen it yet, definitely go read it. I wanted to compare the zone exit data to my rush shot data which I have calculated from play by play data as explained here. If we can find good correlations between zone entry/exit data and my rush shot data that would be an excellent finding because the zone entry/exit data need to be manually recorded and is very time consuming. Thankfully this is a project being undertaken by Corey Sznajder. If we can find useful correlations with data that can be automatically calculated we may not need to do this in the future and Corey can have a summer vacation next year.
Let’s first look at defensive zone exit percentage and how it correlates with rush and non-rush shots.
One thing to note is that my rush shot data is for the full season and the exit% data is for the first half of last year. Also, my rush shot data is only road data to eliminate arena bias and Liles and Fraser also includes their time with Carolina and Edmonton respectively.
Let’s look at some charts to more easily see if a correlation exits.
Ok, this is very counter-intuitive. The defensemen that have the best defensive zone exit percentage have a lower rush shot rate and a higher non-rush shot rate. On the surface this doesn’t make sense. If you are better at carrying the puck out of your own zone you should be able to generate more shots from the rush but that doesn’t seem to be the case. I think what is actually happening here is that to be able to carry the puck out of the defensive zone you have to be a skilled puck handler and if you are skilled with the puck you probably get more time in the offensive zone including more offensive zone starts and more ice time with offensive type forwards. Now, if you are not a good offensive defenseman you probably don’t get many offensive zone starts and get more defensive zone starts and maybe more importantly you play less with offensive minded forwards.
It should also be noted that Fraser is a bit of an anomaly here as his defensive zone exit percentage is well below anyone else’s and his rush shot rate is quite good. If we take Fraser out of the charts the relationship is much flatter and the correlations get weaker. We need to look at more defensemen to get more conclusive results though. Also, I think we will also find that we will get better results for forwards as I generally think it is forwards that drive the offense, not the defensemen.
Another factor in the non-relationship between defensive zone exits and rush shots for might be that often when a team exits the defensive zone they conduct a line change and maybe in particular a change in defensemen as the forwards are taking the puck up the ice. Defensemen may be able to get the puck out of their own end and initiate a rush but are on the bench before the benefits of the zone exit and follow-up rush have materialized. This could result in the lack of positive correlation between zone exits and rush shots. I need to create an “initiator of rush shots” statistic to account for this possibility.
In the comments of the pensionplanpuppets.com article Corey Sznajder provided statistics on zone entries against each defenseman. Most defensemen would likely have significantly more control over zone entries against than they do for creating offense so we might find stronger correlations here.
|PlayerName||RushCA/60||OtherCA/60||Carry% Against||Break-up %|
Now this is a little closer to what we might expect. Those defensemen that have a high percentage of zone entries against being carry-in entries vs dump-ins give up rush shots at a higher rate while also giving up non-rush shots at a lower rate. There doesn’t appear to be any correlation between Carry In % Against and total corsi against per 60 (r^2=0.026) so it seems only the type of shot against is being impacted. I have observed that shots on the rush are significantly more difficult shots (shooting percentage on rush shots over last 7 seasons has been 9.56% vs 7.34% on non-rush shots making rush shots 30% more difficult on average) so players that can limit the frequency of carry-in rushes against and force dump-ins against instead are in fact likely to reduce average shot difficulty against.
The real counter-intuitive observation is that from a strategy/tactics point of view, it might be better to start your defensive defensemen (i.e. the ones that have the ability to limit rushes against) in the offensive zone (for the Leafs this would be Phaneuf and Liles/Gleason last year) and start your strong offensive and weak against the rush defensemen (i.e. Rielly, Gardiner in particular) in the defensive zone . This is the opposite of what the Leafs did last season and generally opposite of what most normally consider doing. It makes sense though. When you are in your own zone you want defensemen who can get the puck and get it out and when you are in the oppositions zone you want defensemen who don’t give up high quality (often odd-man) rushes against. Defense should start in the offensive zone and offense should start in the defensive zone. The focus is generating offense on the rush and limiting the other teams ability to generate offense on the rush. It’s a bit counter-intuitive but might prove to be smart strategy.
I look forward to when the zone entry/exit tracking project gets completed and we can look at a much larger sample with more players from more teams but between that project and the rush shot data I have calculated we should gain significantly more insight into the game and how it is played. We might even come up with some new revolutionary on-ice strategies.