There are essentially three roles in the modern NBA—points (guys who run the offense), wings (guys who play on the perimeter) and posts (guys who play on the interior).
So when trying to see whether a college prospect will struggle to make the transition to the NBA, we've first got to figure out what role he will play in the league.
Most first-round picks initiated offense in college; it was their job to create a shot for themselves or someone else off the dribble. It takes an elite rookie to have that responsibility in the NBA; most are forced to play off the ball as role players.
Adjusting to this new role is difficult; if you have the ball in your hands a lot, it doesn't matter if you have a shaky jumper. But if you're playing off the ball and you can't shoot, then you become an offensive liability, and the other team can play 4-on-5 defensively.
Likewise, while an inferior defender can be hidden on the perimeter, it's much harder to do so around the basket. So while perimeter players are often offensive burdens, interior players are often defensive ones. If your big men can't rebound, block shots and defend the low post, then you will have a tough time having a good defense.
With that in mind, here is a list of 10 guys who might struggle in their new roles in the NBA if they are drafted as highly as they are projected, be they lottery picks who should go at the end of the first round to fringe first-rounders who should be second-rounders.