Castle really is a more athletic JHS w/ less lead guard opportunities and probably a worse overall jumper.
When I watch Castle's set shot, along with his hesitation to shoot, it's pretty bad. Not beyond hope, but he lacks a lot of rhythm as a spot up shooter.
He has zero confidence in his shot, it's a real concern. He's had games where he pulls up confidently and it looks pretty good, and that give me some confidence.
I'm not a expert in shooting form or anything, but his shooting motion seems like the kind of shot that I've seen dramatically improved over time in the NBA.