May 012013
 

I brought this issue up on twitter today because it got me thinking. Many hockey analytics dismiss face off winning % as a skill that has much value but many of the same people also claim that zone starts can have a significant impact on a players statistics. I haven’t really delved into the statistics to investigate this, but here is what I am wondering.  Consider the following two players:

Player 1: Team wins 50% of face offs when he is on the ice and he starts in the offensive zone 55% of the time.

Player 2: Team wins 55% of face offs when he is on the ice but he has neutral zone starts.

Given 1000 zone face offs the following will occur:

Player 1 Player 2
Win Faceoff in OZone 275 275
Lose Faceoff in Ozone 275 225
Win Faceoff in DZone 225 275
Lose Faceoff in Dzone 225 225

Both of these players will win the same number of offensive zone face offs and lose the same number of defensive zone face offs which are the situations that intuitively should have the greatest impacts on a players statistcs. So, if Player 1 is going to be more significantly impacted by his zone starts than player 2 is impacted by his face off win % losing face offs in the offensive zone must still have a significant positive impact on the players statistics and winning face offs in the defensive zone must must still have a significant negative impact on the players statistics. If this is not the case then being able to win face offs should be more or less equivalent in importance to zone starts (and this is without considering any benefit of winning neutral zone face offs).

Now, I realize that there is a greater variance in zone start deployment than face off winning percentage, but if a 55% face off percentage is roughly equal to a 55% offensive zone start deployment and a 55% face off win% has a relatively little impact on a players statistics then a 70% zone start deployment would have a relatively little impact on the players statistics times four which is still probably relatively little.

I hope to be able to investigate this further but on the surface it seems that if face off win% is of relatively little importance it is supporting of my claim that zone starts have relatively little impact on a players statistics.

 

Jan 312012
 

Just wanted to let you know that I have finally updated stats.hockeyanalysis.com to include 2011-12 data though I have not yet included multi-year data that includes 2011-12.

I have also included in this updated zone start adjusted data which adjusts for zone starts by not considering the 10 seconds following an offensive/defensive zone faceoff.  I have included both 5v5 and 5v5 zone start adjusted data and the 5v5 close, 5v5 tied, 5v5 up 1, 5v5 up 2+, 5v5 down 1 and 5v5 down 2 data are zone start adjusted.  It doesn’t make any sense to zone start adjust PP and PK so the 5v4 and 4v5 data is not zone start adjusted.

As always, if you have any issues or questions with anything at stats.hockeyanalysis.com let me know.

As an interesting aside on zone starts, I have noticed that zone starts affect shots/fenwick/corsi somewhat significantly but do not affect goal data much.  I thought this was strange at first but then the explanation became clear when I looked at shooting percentages.

Situation SH%
All 5v5 7.91%
ZS Adjusted 5v5 8.89%
10 seconds after Ozone faceoff 3.04%

Shots within 10 seconds of a faceoff don’t go in nearly as frequently as shots at any other time.  The reason for this is probably that the majority of these shots likely come from the point after an offensive faceoff win.  Also, the goalie is perfectly set and ready for the shot and the defending team has their players in optimal defending positions and are usually fully rested.

So, what does this mean?  It means you can actually probably pretty much ignore zone starts if you are looking at goal data.  Zone starts have very little influence on the rate at which goals are scored.