There is a difference between the dominant scorers of the league and the gunners who score lots of points. LeBron, Wade, DRose, Durant, CP3, Ray Allen, Paul Pierce, Dirk, KG, etc. all dominant scorers at some point in their careers who never had to gun to get theirs. They understand when to shoot and when to pass, how to play within the flow and they get the "big picture" of what the offense is trying to achieve.
It's kind of the difference between Durant and Westbrook as scorers, though Westy doesn't always turn into Westbrick and start gunning every night.
Shabazz doesn't always grasp the fine line between playing aggressive and smart and playing selfish and stupid. He takes bad shots early in the clock. He zones in on his shot and takes contested looks instead of hitting open teammates. He's got so many different tools and can score from almost anywhere on the court that he thinks, "yeah I can score from there" and doesn't have patience. He always looks for his shot and is a bad passer on top of it (twice as many turnovers as assists).
It's really hard to build a cohesive offense that plays together and raises all boats with a wing like that. You'll see the guys at UCLA pretty much ignoring Shabazz as he's open on the wing and try and work the ball inside to lesser scorers because they know he doesn't pass. I don't think it's so much that he's selfish or a bad teammate. I think he just doesn't quite get it. That's a basketball deficiency as much as not having a jumper.