Koch was a starter in the minors. It's kind of interesting. He never made a relief appearance in the minors (with the exception of 4 appearances in 2003), and never made a start in the majors.
I don't know what to make of Castellanos. He's still bad defensively, but he has improved quite a bit this year. Ideally he'd probably fill a DH role and maybe play RF twice a week. Really hard to figure out what teams will pay for that. Maybe Seattle will sign him to play CF.
Yeah, he's only 21. This is two years in a row with poor free throw shooting, but it's also something that should be fixable. I can't see him being Shaq at the line.
Yeah, it's the health I'm worried about. 7'3 with a knee issue that's kept him out for 20 months isn't ideal. He was signed to a big contract after the injury though, so clearly the team believes it won't be an issue.