Check out this post on the new version of Rink Stats. I think Corsi sucks.
I think Fenwick sucks.
I think they suck, not because I'm an old-school, Brian Burke-ian stats hater. I think they suck because when it comes to "advanced" hockey stats, the formula shots + blocks + misses = corsi is lazy and oversimplistic. I think they suck because (at best) they're weak proxies for what we believe is important in a hockey game (puck possession). I think they suck because I know we can do better.
Mostly, I think they suck because they're a constant reminder of the fact that there's so little investment in hockey analytics by teams and by the media. Don't get me wrong, there's fantastic work being done by lots of people on the blogosphere, but until NHL invests in player tracking technology (and hopefully makes it publicly available) we're going to be stuck using weak proxies like Fenwick and Corsi to measure possession.
In this post I don't intend to bring you to my side. You probably clicked on this post precisely because you know what Fenwick and Corsi are and find them valuable. I agree with you on that. They're infinitely better than plus/minus and other run-of-the-mill stats. But until we get player-tracking data and other more sophisticated stats, I think it's important that we understand how to properly use Corsi and Fenwick.
The point of this post is to convince you that Corsi and Fenwick don't do a particularly good job of predicting who will win hockey games, and they aren't any better at this task than the traditional shots-on-goal statistic. I also hope to build our understanding of the types of questions that Corsi and Fenwick can answer and when it's appropriate to use them to build narratives about games. Right now I'm mostly concerned with team-Corsi and team-Fenwick, not individual player Corsi/Fenwick, but in the future I'll hopefully dive into the value of C/F on assessing player performance.