What is ‘open play’ hockey?

In a series of recent posts at mc79hockey.com, Tyler Dellow discussed a new concept (to me anyway) that he called ‘open play’ hockey. In a post on “The Theory of the Application of Corsi%” he wrote: I have my own calculation that I do of what I call an open play Corsi%. I wipe out the faceoff effects based on some math that I’ve done as to how long they persist and look just at what happened during the time in which there wasn’t a faceoff effect. This sounds strangely similar to my zone start adjusted statistics where I eliminate

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Are coaches any good at identifying defensive players?

A while back I came up with a stat which at the time I called LT Index which is essentially the percentage of a players teams ice time when leading that the player is on the ice for divided by the percentage of a players teams ice time when trailing that the player is on the ice for (in 5v5 situations and only in games in which the player played). LT Index standing for Leading-Trailing Index. I have decided to rename this statistic to Usage Ratio since it gives us an indication of whether players are used more in defensive

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Face offs and zone starts, is one more important than the other?

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%

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Further investigation into impact of zone starts

Tyler Dellow has a post at mc79hockey.com looking at zone starts and defensemen and if you read it the clear conclusion is that zone starts seem to matter quite a bit. In the third chart you can see that defensemen who get the most extreme defensive zone starts have an average corsi% of 44.7% while the average corsi% for defensemen with the most extreme offensive zone starts is 53.3%. This would seem to indicate that for defensemen zone starts can impact your corsi% anywhere from -5.3% to +3.3%. This is far more significant than I have estimated myself using a different methodology so

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Do zone starts really matter and if so, how much?

I often see people using zone starts and/or quality of competition as a way to justify any players unexpectedly poor or unexpectedly good play. Player X has a bad goal or corsi ratio because he plays all the tough minutes (i.e. the defensive zone starts and against the oppositions best lines). I am pretty certain that quality of competition is vastly over emphasized (everyone plays against everyone to some extent) and is vastly overshadowed by individual skill and quality of teammates, and I think zone starts do as well. Eric Tulsky at NHL Numbers.com posted a good review of the

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Taking a look at quality of competition

When I updated stats.hockeyanalysis.com this season I added new metrics for Quality of Teammates (QoT) and Quality of Competition (Q0C). The QoC metrics are essentially the average Hockey Analysis Rating (HARO for offense, HARD for defense and HART for overall) of the opponents that the player plays against. What is interesting about these ratings, as compared to those found elsewhere, is that I split the QoC rating up into offensive and defensive metrics. Thus, there is a QoC HARO rating for measuring the offensive quality of competition, a QoC HARD for measuring the defensive quality of competition, and a QoC

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Zone Starts: Why We Shouldn't Care

There was a twitter conversation between Gabe Desjardins and David Staples last night in which Gabe suggested that Daniel Sedin’s heavy offensive zone start bias resulted in an additional 7-9 points that he would not have gotten if his zone starts were more evenly split between offensive and defensive zone.  When I saw this I immediately though that seemed like a really high number so I decided to take a look though the play by play sheets and see how many of Daniel Sedin’s even strength points came from a faceoff in the offensive zone.  Of all of Daniel Sedin’s

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Zone Start Effects on Stats

Over the past week or so I have talked about a simple and straight forward method for taking into account variations in zone starts.  The method is to simply ignore the 10 seconds following an offensive or defensive face off.  By adjusting for zone starts in this manner we can see a fairly significant impact on stats and today I’ll take a look at what gets impacted and how. To do this I took a look at 3 year data using the 2008-09, 2009-10 and 2010-11 seasons.  Using 5v5 data for players with at least 1000 minutes of ice time

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Stats.hockeyanalysis.com updated

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

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Adjusting for Zone Starts

One of the biggest omissions in my player rankings is making adjustments for zone start differences.  We know that Manny Malhotra has a significant bias towards starting his shifts in the defensive zone and that his teammates Daniel and Henrik Sedin have a significant bias towards starting their shifts in the offensive zone.  The result is Malhotra will unfairly be penalized for giving up more shots and goals against simply because he starts more often in the defensive zone and the Sedins have a huge advantage in generating shots and goals because of how often they start their shifts in the offensive

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