Because he's an athletic freak, good defender, and seems to have an "it" factor.
I didn't like his hesitation to shoot open jumpers at times last season. I believe his lack of confidence in the jumper is unwarranted.
I like his form. His shot looks good to me, he just needs to confidence to to pull it when he's open. That could be a factor in his pro career.
Another thing he's got to overcome is his free throw shooting. It's a nightmare to watch. He's going to get hacked on drives to the hoop until he can learn
to fix that. If he doesn't overcome, or it takes him a long time this will greatly limit his potential.
If he's able to over come those two key issues so that the defense has to respect his jump shot, and can't foul him on drives to the hoop. Look out.
He could become a monster in this league. The "it" factor seems to be there. He has the look, and feel of an elite NBA player. It's like he expects it.
He's been preparing for it all his life.