Castro is too much for Cashner, considering he's a FA after next year. Cashner has been horribly injury prone. He's on the DL all the time. He has had very mediocre success, hasn't really eaten innings, and has been a big disappointment to San Diego, considering what they gave up for him. Rumor has it that they were praying Ian Kennedy wouldn't take the QO and are grateful he didn't. Next, they'd like to get rid of Cashner, but the price may be taking Shields, too. But all things considered, I don't think I'd give up Castro. If they'd give him up for Underwood and another minor prospect, fine.