I like alot of guys that got injured this year as sleepers. Hughes, Wainwright, Chris Young, Carmona, and Gallardo come to mind. Notice not one of these guys had an arm injury, but rather a different part of the body.
Matt Cain - he's very talented, but has disappointed.
Gil Meche - He's had a good season if you forget his dreadful April.
Andrew Miller - A guy to keep an eye on for the rest of the season. He's pitched well at times and terrible at others. Still talented.
Anthony Reyes - an ultimate sleeper for deeper leagues. Things might click for him in Cleveland. Or he'll bust. Again.
I'll have to look at this a bit deeper after the season, but this is some that I've thought of.