I'm always looking out for different ways to express goalie performance, and ran across an interesting one that I'd never seen before while going through the archives at Tom Tango's Inside the Book blog. He wrote a brief Wall Street Journal article that expressed goals against average in terms of goals against per 30 shots, rather than goals against per 60 minutes of play. That gives a metric that is pretty much just a translation of save percentage (GA/30 = (1 - Sv%) * 30), but the advantage is that it results in figures that look like goals against averages. GAAs are more familiar and intuitive for most people to understand than save percentages, and allow a better sense of the actual difference between goalie performance on a per-game basis.
There is one slight tweak I would suggest to Tango's number, and that is to adjust for special teams. I'd suggest calculating even strength goals against per 24 shots and goals against per 6 shots on the penalty kill, which reflects the typical 80/20 split between non-PK and PK shots, and then adding those two numbers together to get a special teams adjusted goals against per 30 shots number.
Here are the league's top 20 goalies last season based on this metric (min. 35 starts):
1. Tuukka Rask, Boston: 2.17
2. Ryan Miller, Buffalo: 2.21
3. Jaroslav Halak, Montreal: 2.26
4. Evgeni Nabokov, San Jose: 2.34
5. Tomas Vokoun, Florida: 2.36
5. Ilya Bryzgalov, Phoenix: 2.36
7. Jimmy Howard, Detroit: 2.37
8. Henrik Lundqvist, N.Y. Rangers: 2.41
9. Jonas Hiller, Anaheim: 2.44
10. Miikka Kiprusoff, Calgary: 2.45
11. Craig Anderson, Colorado: 2.50
12. Cam Ward, Carolina: 2.53
13. Tim Thomas, Boston: 2.57
14. Chris Mason, St. Louis: 2.60
15. Johan Hedberg, Atlanta: 2.61
16. Martin Brodeur, New Jersey: 2.63
17. Roberto Luongo, Vancouver: 2.64
18. Marty Turco, Dallas: 2.65
19. Antti Niemi, Chicago: 2.67
20. Jose Theodore, Washington: 2.68
I think by the majority of measures Miller was a deserving Vezina winner and First Team All-Star, so kudos to the voters this year for getting it right.
