Castle helped lead his team to a le at UConn. He has good size and a high BBIQ. He may not be an athletic freak, but he has good athleticism. He sells out on the defensive end of the court and takes it personal when his man scores. He has a fire, passion, and hunger to be the best and to win. He doesn't just go through the motion, pout, sulk, or rely on his athletic ability. He puts in the work on and off the court.
Yes, I want Castle at 4. The only other player I would take at 4 would be Sarr, if by some chance he fell that far. That isn't happening, so take Castle.
Then, at 8, you can take an athletic freak in Holland, also a defensive stalwart, or go with a sharpshooter.