Peaked or not, if the staff can get him a few more shots while on the court, and keep him on the court for more than 19 minutes per game, he'll benefit. And if he rebounds like he did at times last year, you got a beast on your hands.
Maybe it's a time thing, maybe it's the scheme , and maybe it's confidence. But there are many ways Justin can be a bigger part of the offense (and possibly defense). If they play fast and find Justin, he'll get a higher percentage of shots; he gave up the ball at times in the halfcourt, like a guy who was thinking too much.