It's not so much weaknesses in his game at OT as it is where I think he's best suited to play.
He looks much more comfortable moving down the LOS than away from it, his reaction time is terrific, and he can work his way through traffic and hit targets. To me, those traits, combined with his excellent play recognition, scream center.
People will tell you that he's not OT material because he lacks length and contact balance on the EDGE, but I think that's overstated. It's just that OT isnt his best position. He can likely be a fine RT, but I'm not looking for "fine" or a RT in the first round.