I don't know how well he tracks the ball when in the outfield - on the popup today it wasn't clear that he did, particularly on the initial jump. But in addition to tracking, you want your CF above all to be both decisive and correct*, and on that play he slowed up then sped up again, and that's going to cost now and then.
He's only got 13 complete games of experience in CF so I wouldn't go so far as to say he can't play it. If he finds himself playing games again for St Paul, that would be a good place to hone the skills in center.
* Jake Cave for example tended to be decisive but incorrect at times, which is probably worse than the other way around.