Big Baby will always be a solid energy guy off the bench who can have a big game now and then against an opponent with an undersized / untalented / soft frontcourt.
He'll never be a starter who can average more than 10 points a game or more than 7 or 8 rebounds a game efficiently. He just doesn't have the body for it. If he were 2 inches taller and 40-50 lbs lighter, then sure. As he is, no.
It's pretty nonsensical to say he'll never be a starter averaging more than 10 a game when he started about 30 games last year including playoff games and averaged well above that. Also, his per36 rebounds was about 8 (to go with about 13 points). Can he be an above average starter? I don't know. Can he give you more than 10/7 as a starter? Yes.
Notice I said "efficiently"
He's not that inefficient a scorer. Were you claiming that he's an inefficient rebounder?