I am pretty hopeful for Sarr. Skill-wise, he's most likely the best of the 3.
I think Moore is always going to be a guy who, at best, you sub in for a 3-5 minute stretch with an equal period of rest. That could mean up to 25-28 minutes a game with TV timeouts. The first 7 games will show me. Those are his minutes to lose. He has yet to go up straight on D. He comes over with his arms. Some of that is due to stamina - it takes physical and mental discipline and stamina to consistently go up arms straight. I'd like to see him do it on 3 straight possessions at some point in those first 5 games. So far, after two years, I've seen him go up straight once or twice. He's great on help D around the rim. It's the man-to-man post players he fouls pretty much every time. Can't do that to keep/earn minutes.
Sam is almost the opposite of Moore defensively - lacks ups, but positions himself well. I think, if he can continue to move his feet, he'll be an ideal defender against shorter post players. It limited minutes, he seems like a good rebounder on the defensive end. His hands seems okay to good. I'd like to see him learn footwork post moves that leave him bunnies or being fouled. Not sure about his passing out of the post.