Agree with this sentiment about waiting to see how the player responds and plays at this level before speaking in absolutes. Benny is the most recent example of that (still think he is way better than he has shown).
In general, I can say from experience that tweaking a player's jump shot or "working out any kinks" is way, way more difficult and time intensive than many here think. To a somewhat lesser degree, so is improving a player's handle. I anticipate that there will be examples cited of player X who was able to improve this kind of stuff, and that's true. It's just not the norm to see significant improvements, despite the exceptions.