Well, different appraisals and opinions are part of the fun of this game...
I-Rod and Gonzalez are both question marks, but I'd much rather have Rodriguez. Both seem to be moving in the right direction, but Gonzalez just doesn't seem like the same mvp-caliber player we used to know. With so much talent at of, I'd say he's too much of a gamble. Even if you like the deal, it wouldn't hurt to contact those Pierzynski or Santiago owners (not to mention frustrated Lieberthal owners) and see what kind of return you could get.
I agree about Ishii resembling the proverbial ticking bomb. We knew when he came over before the season that he wasn't a control pitcher (minor aside: why is it that Japan has lots of excellent control pitchers, but the starters who come to the US always bring a reputation for being erratic with them?), but this is more stress on his owners' nerves - not to mention Dodgers fans - than we ever imagined. It's amazing how much he's gotten away with so far. timkell's right - a package of Ishii/I-Rod for a starter and a solid bat would look very good. He could still turn it around, of course - he's shown great smarts and poise. However, if you can find a good offer based on his wins, I'd move him.
Leiter's been on-again off-again, but I'm not aware of any injury. He did adjust his delivery slightly recently, though. I think he'd make an upgrade from Ishii. Finding a solid bat seems more important, however.