One of the things I've always wondered about: Hasek posted a 0.928 EV Sv % during 2007-08 (for comparison's sake, that was the same as Miller when he won the Vezina in '09-'10). His overall sv% was brought down by a pretty bad PK sv % (0.822), and less by a thoroughly mediocre PP sv % (0.848).
I don't know whether Detroit had a particularly bad penalty kill that year (I doubt it; Osgood's numbers were pretty good), or there are some issues just due to sample size, or whatever. My theory is that while Hasek's aging left him still in the elite tier of goalies at even strength, his quickness and side-to-side movement left him somewhat vulnerable while on the penalty kill. This, plus perhaps some bad luck or a really weird variance, was responsible for his overall low save percentage that season. EV Sv % is usually the best (unadjusted) single indicator of goalie skill, but I think there's a little more at work during Hasek's final years, especially his last.