I had him his magical year where he almost went 20-20. 20 steals from a catcher is unheard of, well not unheard of, but truly rare. While he won't be running much in NY (I'd say like 10 SB max), he definitely can produce. In 2008, Torre played him ALOT, I think overworked him at some points, playing him at 3B when he should've had days off because Torre believed their lineup needed his offense. Also, expectations were high for him after 2007. LA expected him to be an all star every year for them after that and I think that pressure kind of got to him. Then he also got injured.
He's dealt with being overworked and injured and I believe if Girardi handles Martin right he can be a top 5 catcher. Plus when he came to NY, despite the big publicity of NY, no one really expected much out of him. He's gotten healthy, relieved pressure, fresh start, not to mention a better ballpark to hit in, and a better lineup.
I'd say 20-25 HR, 80-90 RBI, .280-.290 are about what you can expect out of him. I may be a bit optimistic though because I've wanted to see him do well since I had him in 2007.
"Chuck Norris has been known to throw a baseball 100 mph. I've been known to throw Chuck Norris 100 mph." - Brian Wilson