He can improve on little facets of the game as mentioned (FT%, long arm defenders) but can improve beyond that? NO.......and that's not a bad thing. He was an all-star, #4 in MVP voting and had his highest assist total in his career. Not to shabby for a 30 year old who's a 11 year vet.
“I think he’s going to be a star. And as time goes on, he’ll be the face of the Spurs, I think.” ---- Coach Pop on Leonard