IIRC -He hurt his shoulder going into a base while still in the minors so they swapped him and Jung 2nd and third because the shoulder. At the time they said it could take a year or two for it to regain full strength, if it did. So he was tooling along as a 2B then they signed Torres but also figured Tork was toast so he was a 1b, and then when when Tork wasn't, it was - well share the ABs as best we can, and then finally: "Well how is the arm doing now? Try 3rd again" Last year once they put him back there he seemed to be throwing OK and there were no issues, so he is back where he started. He doesn't have anything like a cannon, but he gets rid of the ball quick and he's accurate.
I'm guessing some people got a little misled looking at statcast data because you just don't try to throw max effort at 2b so his throwing velo looked pretty low, but at third he was hitting upper 80s, and with regular throwing there who knows he might loosen up and be able to add to that.