Guess I just disagree, I can see him starting over all 3. Certainly has more upside than Poole and Livers, don't think that's really debatable. Already a better shooter than Matthews and Livers. Better finisher than Poole and Livers.
Here's my skill pecking order
Handling - Poole, Matthews, Cain, Livers
Shooting - Cain, Poole, Livers, Matthews
Rebounding - Cain, Livers, Matthews Poole,
Passing - Poole, Cain/Matthews, Livers
Perimeter Defense - Matthews, Cain, Livers, Poole
Cain is near the top of the list for most categories, not hard to see why he will play. Versatility more than any other player as a 2 way option. Matthews has a LONG way to go in terms of shooting, Poole has a LONG way to go defensively and athletically, Livers has LONG way to go in terms of ball skills. Cain just needs strength at this point