I did look at the games:)
Again, I am not saying he is bad in the 3 pt shot department, he is decent, but most of his points come from elsewhere, so I think it's improper to say he has 20 or 20+ JR, or that he is one of the best of all time. His mechanics are the same also because of his physical strength, he really does not need to alter his shot most of the times, at least not because of the range that he shoots from.
Anyhoo, going back to original subject, I think it may happen that players are awful from 3pt territory and decent from mid range. Just as it may happen that players are very good at range shooting and not that good at point blank lay-ups. All the motions require techniques and a lot of practice, especially for professional level.
In BB, it's debatable what can happen but if a player reaches 10 JR, it;s almost impossible to have atrocious JS