Look, this is really ****ing simple.
Exum has a unique combination of extreme speed, quickness, and stride length. It's why he is so damn good at staying in front of players in isolation and getting into the paint. The guy has next to no offensive talent that would help him get into the paint. He is a below average ball-handler as a guard, he has hardly ever attempted any off-the-dribble pull-up shots (much less made them), and he has a very poor C&S 3pt game.
If a player like Exum can get into the paint and have a 38% FTR, it's because he's really damn athletic. Everyone knows what's coming when Exum has the ball, yet they still struggle to keep him from where he wants to go. To argue otherwise, you are just being a moron. Maybe you can get real picky as to what is the "elite" standard, but to call him an average athlete? Kindly **** off because that isn't an arguable position.