I don't view Castle as most guys. He's a top 5 pick and choose to be a role player in college to win, and already has an elite offensive weapon, being 15th in the NBA in FTr (exclusive of part-time Centers, #27 overall). That alone give him more of a shooting cushion then most guys ever get.
Cade shot 31% and 29% from 3 his first 2 yrs (76 games), with TS% of 50% and 49%. Castle shot 29% on similar volume with a TS% of 52%.
Castle improved his TS% every month from Dec to April, and put up 19.3 on .46/.30/.72 in 25 games as the guy.
Cade put up 17.4 on .42/.31/.85 in 32.6mpg his first 64 games as the guy. Castle was 14.7 on .43/.29/.72 in 26.7mpg in 81 overall with an inconsistent role.
Really not far off. Cade improved to a .35-.36% shooter, Castle can absolutely get there, especially with the gravity of Wemby/Fox and hopefully Harper. I don't expect Castle to ever be a sharpshooter, but near league average? Yeah.
Not saying he's Cade, obviously will have a different role, but another top5 guy of similar size who improved. Choosing UConn shows he's fine playing a role and he'll work at it. He's not Sochan or Wesley, his ability to get to the line will give him more space.
Castle's trade value may be at peak right now, but he's not done improving as a shooter at 20y/o.