The elections in 09 were heavily turnout based.
So were elections in '08. And '07. And '06.... Elections are turnout based. That's only a negative when your base doesn't turn out as much as the other party's.
The Democratic incumbent Westchester County Executive lost by double-digits. I'm sure that was just "heavily turnout based" too. Republicans in New York state had nowhere to go but up after 2008.
I can't speak as much for Westchester as I can for Nassau, but Democratic turnout in 09 was anemic. Bad turnout in one year doesn't exactly = changing of the guard or anything like that.