The defense was bad, and Lawson did blow by guys a few times, but most of his damage came off the pick and roll where no one showed to stop the ball, and no one rotated over, so he just went around the screen all the way to the rim. A shot blocker would have been nice to try to clean some of that up, but the problems were mostly scheme or lack of understanding of the scheme.
The offense wasn't that good either, which is why Marion didn't play much down the stretch, because he doesn't offer much on that end.