i've sort of come to the conclusion that you draft athletes with length and if they have good mechanics but may not have the greatest shooting production ever, take your chances. if they don't improve, you may still have a guy who can defend, get out in transition, etc. if they improve and become a 40% 3pt shooter, you probably have an all-star.
now some guys you can see they can flat out shoot - guys like Klay, Steph, Redick, Korver - these pure shooter types that don't require much improvement. Herro and Cam Johnson in this draft.