I wanted to try and get a better idea for Stephon Castle's shooting prospects and the odds that he'd be a decent shooter. People cite his FT% often, but using that as a sole factor seems inaccurate. For me at least, trying to get an understanding of "touch" and 3 point accuracy looks at 4 factors - FT%, college 3 pt%, college 3 pt volume, and college midrange %. That said, Castle scores poorly in 3/4 categories - while his FT% is acceptable, his 3 point % (27), 3 point volume (75) and midrange accuracy (35%) are extremely worrisome to me. Looking at these factors, I would expect that he would not project to be a good shooter moving forward.
These are the results of a quick database search. I used Bart torvik to look for all 1st round draft picks (excluding bigs) in the last 17 years with the following:
FT% > 75
Midrange % < 40
3 point volume < 100
3 pt % < 30
Of the 17 hits, there were 3 guys who ended up turning into good shooters by their pre-draft season and then obviously became good NBA shooters
Buddy Hield (Fr), Jalen Williams (So), Mikal Bridges (Fr)
Of the 14 others, 6/14 became league average or better shooters:
Kawhi, Alec Burks, Oladipo, Delon Wright, Grant Williams, Pascal Siakam
Unfortunately, the 8/14 other players who did not become league average or better shooters all busted or are on their way out of the league
If we turn the FT filter down to 72%, we add Jaden Ivey, Kobe Brown, De'aaron Fox, Michael Kidd-Gilchrist, and Jeff Taylor; none of these 5 are what I would call good shooters, although maybe there is some hope for Fox and Ivey in the future
So these results actually are more optimistic for Castle than I would have thought. I basically assumed that he had virtually zero chance of becoming an acceptable shooter with his metrics, but in truth I think that there is some precedent that he can get to at least league average. That may be enough if he is used more as a secondary creating POA defender like Jalen Suggs. However, this list also suggests that if he does not develop into a league average shooter, there is a decent chance he will bust out of the league along the likes of Nassir Little and MKG.