Another problem with NY is that, quite simply, they are old.
Ichiru, A-Rod, Jeter, CC, Petit, Rivera (not this year, but still), Raul, Chavez, Tex, Swisher - this would have been an unbeatable team 10 years ago, maybe five years ago. Now, they are a bunch of guys statistically past their prime. One of the key problems with guys statistically past their prime is two fold.
One, they get hurt. A lot. Old guys get hurt faster, and they heal slower.
Two, their talents do erode. None of those guys is the guy they were five years ago or 10 years ago. Their eyes are not quite as sharp, their arms not quite as strong, their legs unable to carry them quite as fast.
At one time, that would have been one hell of a lineup. Now, a bunch of has-beens. This is a problem the Yankees seem to run into quite a bit since King George and now his son have taken over - they seem to be more interested in collecting names, rather than talent. It works sometimes, but other times, they spend a lot of money for disappointment.