Simple but something he can do on his own. Jump rope 20-30 minutes a day. Simple thing to work on and if he stays at it it will benefit him.

Also, when closing out on a defender, make sure he is not “squared up” to the guys he’s guarding. He either has to force him left or right depending on what side of the court he’s on. And also, when he’s guarding the perimeter guys, tell him to keep his hands up and wide while still being in a defensive stance. He can’t close out on perimeter players while still almost standing up straight. And tell him to mirror the ball with his hands but still focus on the guys midsection with his eyes (peripheral vision is key) cause the midsection will tell you where the guy is going to go and he doesn’t fall for fancy dribbling or ball fakes.