I somehow got the impression that Exum's legs had a little lead in them. For example, when he stole the ball and went full court for the layup he just didn't have that spark
wasnt lead in his legs ,it was a sweet move not to let anyone fly behind him to block his shot ala Hayward ,Lebron..by using his length and reach to lay it over the front of the rim and use his body to shield the chase down