Sitton only missed 3 games a piece in each of the past two seasons. By comparison, Bak missed 4 games last season. Bulaga, something like a million. I wouldn't call Sitton "injury-prone."
Sure, it's a young man's game. But nothing can be substituted for experience, as they like the say. In the Super Bowl, in the clutch, the game on the line, I'd rather have Sitton in there protecting A-Rod than McCray.