One of the statistics that I use a lot in evaluating player performance is Corsi – a measure which basically works out to a shot plus/minus on one end of the rink or the other (it includes missed shots and blocked shots). Others prefer Fenwick (the same measure, minus blocked shots) or straight shots (if it doesn’t hit the net…) but all three show essentially the same thing: which end of the rink the puck stays in.
There are a lot of people out there who don’t think this is a fair indication of player performance. The most frequent comment made is that players of different abilities are more likely to score on different shots, or that defencemen can somehow limit shot quality against. These are undeniably true, but when you consider players as five-man units I think this gets watered down, and I’d argue it’s really a rather small point in comparison to the most important one – possessing the puck in the offensive zone, or keeping the opposition from possessing the puck in the defensive zone, which are both measured by the shots metrics I’ve listed above.
In an attempt to improve our understanding of the game and give fans access to the kind of information NHL teams track, fans of select teams have been tracking scoring chances all season long. This started last season with Dennis King tracking the Oilers, but has expanded to include other clubs as well. On Friday, Vic Ferrari of Time On Ice, who provides a lot of the scripts for and a big chunk of the brains behind advanced statistics, put together a chart comparing scoring chances to the shot ratios to see if the ratios did a good job of showing who was generating scoring chances.
Here’s the chart for the Edmonton Oilers:
To see the full-size chart, click over to Vic’s site.
The pattern there is undeniable, and shows up in the correlations. According to Vic, the Fenwick number above has a 92.0% correlation with scoring chances, Corsi has a 90.0% correlation, and shots alone has an 89.0% correlation.
That may not be conclusive, but it’s compelling evidence.
Also of interest, to the shot quality club: the numbers that include missed shots had the highest correlation. One would assume that the team which did a better job of getting their shots on net would have a better matchup with scoring chances (given that the team missing more shots would, logically, have less accurate shooters. That turns out to not be the case.
This is a very strong indicator that Corsi/Fenwick and the shots ratio are important player metrics on an individual basis.