TJ surgery is so common now, I wouldn't stress it just yet. If you own him in a dynasty league, you might be safe. A lot of healthy pitchers (high school, college, etc) get it just to avoid complications if they make it pro.
Think about the list of guys who have had TJ surgery recently and it seems 50/50 as to how they perform after: Wood, Smoltz, Dempster, Mo Rivera, Gagne, Gordon...
Who knows, maybe Carpenter comes back as a closer?
And, they are starting to think that pitchers are coming back stronger - at least, a lot of the pitchers who have had the surgery say they are throwing harder...
P-Baker, Gregerson, Meche
DL - Zimmerman, Volquez