Definitely taking the under.
First of all, pure probability is against it. Looking at the history of the league, very few players average over that so soon in their careers anyway. So it's always smart to take the field on this one, regardless of how you feel about Warren as a player.
Second of all, I'm not high on Warren. In fact, I really, really hope we don't draft him. I've seen him in person more than any other player besides Jabari Parker (I live in NC), and I really don't think he is going to pan out. He is a high volume, low efficiency shooter. He's also a bad passer and ball handler. No thanks.
(Seriously, all you people saying he has a touch from everywhere on the court, have you even watched him? He can't shoot from beyond the college 3 point line at all. His shooting numbers are TERRIBLE. He just scores a lot because he shoots a lot. Although he is pretty good at scoring close to the basket, all of his long range shooting numbers are abysmal. He can't even shoot free throws.)