Had to reread that to make sure that I didn't have it backwards.
How has he been that bad???
From when I watch him:
He has the same effect on the offense as LeBron always has, and how Harden did for a few years in Houston. There's just nothing going on - anywhere - in terms of movement off the ball when he has it. Everyone is standing around, giving him space to play his game.
The shooters around him are not good enough to make that work. The Rockets had it figured out when they literally stacked the team with catch and shoot guys around Harden and CP3. The Mavericks don't have those. Luka isn't the caliber of player that LeBron is, so he's not elevating guys' games with his play either. And this is assuming he hasn't mentally lost it at any given point, when he simply reverts to a 1 on 5 player who complains to the refs while he's doing it.
Compounding all of it, Luka is *bad* defensively. Teams can get whatever they want by putting him in their action, and KP is also a poor PnR defender. Any team that has the ability to put both of them in that action simultaneously is simply going to feast.
Luka's talent is breathtaking and he has all the potential in the world, but I'd call the mental side of his development, or lack thereof, a major disappointment.