It really doesn't make much sense to get upset about overall scores without analyzing the scores that are being averaged.
Like with Melo and Lebron. How is it surprising that Lebron is so many points above Melo? Melo has better post moves and a better jumper. Lebron is probably better at everything: on defense, on speed and jumping, on strength, on passing, on penetration.
Neither is that great from 3.