He should definitely be a consideration for the Celtics in the draft. Especially in the late first or second round. I've heard all the talk about him, and yes it's not all great. He has an NBA body already, he is a real rim protector with great size, and only a fair rebounder. I've never heard he's a locker room problem.
We're not talking about a finished product here, he's a kid. Kids make mistakes, as we all know. He could grow into a solid NBA center. Brad Stevens would be just the right coach for him, and these Celtics would set a nice example for him.
Invite him in when the time comes and work him out, can't hurt.