While I agree that it's a bit surprising how serviceable he became, his minor league numbers really aren't that bad. He was above average as a 22 year old in AA and league average as a 23 year old in AAA with good contact numbers, as a shortstop. While he clearly wasn't fit for the position, those kind of guys usually get a look in the big leagues; moving him off SS seems to have done him a big favour, as he's about an average to slightly below defender in other places around the diamond.