Not everybody can learn to shoot at a high percentage....that's number one. Number two, 100% the student has to put in hours and hours and hours daily...not twelve hours one weekend. Nobody, can do it for you.
Back to one, not everybody has the physical abilities to execute the preferred mechanics. Their wrist, their hand, their elbow, their shoulder, something won't allow them to do what you'd like. They have to find their own way...what works for them and put the time in.
Number three, maybe the most important part..once you develop the ability now, you need the mentality. Some guys can make 100 free throws in a row and shoot 59% in games. Some people don't want the burden of scoring, the responsibility....being "the man". Lots of guys can score as the 4th best player on the team...as soon as you design plays to get them shots they start throwing up bricks. Not to mention the difference of being defended by the other teams best defender versus being left unguarded. Lots of wannabes melt down versus defensive pressure.
Shooting is complicated and very difficult to teach. You can get 100 kids looking pretty good in a week long basketball camp. That doesn't make them shooters.
If it was easy, obviously there would be a lot more shooters. Gophers got one shooter and he doesn't hunt shots. (or have plays designed to get him any)
Coffey, certainly should explore the draft but like several have said he is not in most all evaluators top 75 lists of prospects.