Nothing I've read indicates he can't be at least average defensively there. Arm is fine. And rated a 60. He was still even playing SS more than half the time when he was in the field and not DH at New Hampshire.
Interestingly at Buffalo they have him ating a mix of 2b, SS and 3b. At Buffalo he has the most innings at 2b. That's probably just to ensure he got in there every day when Clement, Barger and Schneider were all there at the same time.
The thing is, no matter who plays 3b next season...it will be a step down from what we've seen from Chappy over the past two seasons because Chappy is just that much better defensively than nearly everyone and to many whomever plays at 3b will be seen as bad, at least initially, as a result.