This is because Parker doesn't even attempt half the amount of 3's that other point guards do, thus also meaning he does not spread the floor like a point guard should and his 50%FG isn't really as impressive as it sounds. True shooting percentage is better to go by. You are right, though, he is good at what he does. He is a scoring point guard. He is good at scoring. The problem is that he doesn't spread the floor to the 3(which is nuts for a PG), he doesn't have good court vision, and more importantly, he can't defend.