Look at a guy like Paul George.
Last night, Dude Scores 18 points, grabs 14 rebounds has 7 assists 2 steals and 2 blocks. He didn't shoot particularly well but he played suffocating defense on Melo all game. No matter whether George is shooting well or not he finds other ways to help his team.
Melo doesn't consistently have this mentality. If he did it would show on the court.