I agree about the defense. However, I think the decrease efficiency between his college and pro days were due to his knee injury. He was noticeably tired on the court which leads most players to slack on the D end compared to the offense side of the ball. Also, I wouldn’t be surprised if the FO wanted him to take it easy on the D end. I was worried all season that he would go up for a block and come down on a foot... leading to another knee or ankle injury.
I think a healthy and conditioned Zion drastically picks it up up on D.