Thing is, you're putting Schilling over some really good pitchers in their own right who weren't getting rocked (Zambrano, for example). The risk of Shcilling's age and that he may never be quite the same reduce his value.
Harden may indeed be lower if his injury keeps him out. But he's not lower than Haren or Burnett just yet! And if you are going to say that Harden is unproven and should be lower, then by that logic you should also bump down Willis, Bedard, Hernandez, etc. PArt of looking at pitchers is trends. You expect a pitcher to improve as he matures until a certain age (Harden in that group), while older pitchers have to be watched for dropoffs and injuries (Schilling in that group). Frankly, I don't see that much of a difference between the career trajectories of Willis and Harden. Why should one be so much higher than the other, when really both have only had one successful full year under the belt. Wins and ERA are not really under the pitcher's control, and so are not the best measures.