If he didn't have shooting concerns he'd be a top 5 lock no matter the draft. Seems like most of the lotto picks have shooting concerns lately. People loved the Thompson twins and Black, and Bilal last year and they had even fewer shooting chops, in a better draft class.
If you watch him play and the admittedly rare times he shoots, I really don't know what people see that makes them so certain he'll never be respectable from three point distance. Feel free to save this post, I will be stunned and eat all the crow if a lack of even an average catch and shoot game ends up washing Castle out of the league, or makes him a fringe player. There is a much better chance he becomes an above average shooter and >40% on open catch and shoots imo.
Sheppard would be a very nice get for the Jazz.