Per Anthony Andro, Tommy Hunter has a left oblique strain, which means he's doubtful to be ready to be in the Ranger rotation by Opening Day.
Presumably, he'd be good to go by the middle of April, but with a bunch of viable rotation candidates and few slots, I susepct the Rangers will have Hunter start the season on the d.l. and do a rehab assignment in AAA.
The question then becomes...who takes his place? I'm guessing that C.J. Wilson, Matt Harrison, and Brandon McCarthy are now vying for two spots, not just one, come Opening Day. I'm not sure how this impacts Wilson -- if the team thinks Hunter will be back quickly, and wouldn't otherwise have Wilson in the rotation, I can't imagine they'd want to have him start the season in the rotation only to put him back in the pen after 2 starts.
At this point, I'd bet on the season starting with Wilson in the bullpen and Harrison and McCarthy in the rotation, although I wouldn't bet a lot on it.