I think, after the past 2-3 years, I have come to realize that about 95% of the time, major-injured (i.e. Tex, Grandy, ARod, Jeter, etc) players come back and perform well below their career norm for the majority of the season.
I understand it's nice for the Yanks to get those names back in the lineup, but really, that's all they are, names.
Not only that, but their replacements right now (Brignac/Nix, Youkilis, Wells, etc) are all starting to find their water level. And it's not like Grandy/ARod/Jeter are due back anytime soon. All the while, Tex is hitting .184/.245/.409 since he's come back, so he's hardly bolstered the lineup.
Nix is hitting .250/.316/.302, Youk is hitting .235/.318/.367, and Wells has completely fallen off a cliff and has the exact same OPS as he did last year at this point (keep in mind his OPS on the morning of 5/1 was .911. He's down to .682.
The Yankees offense has been nothing short of putrid, and even with the returning guys, Tex and Youk (.176/.263/.265 since returning from DL) have shown that you're not guaranteed to get much production from them either.