Good topic CD!
Most high school players are not drafted or get college opportunities because they are perfect at what they do. They show an ability to be a better pitcher or hitter over time at the next level.
Often heard is why don't they just leave him alone. You might be getting the job done but the next step up you will not. That is why we often hear complaints when players have done well in HS, but don't get looks from top college programs or why good college players don't get drafted high or drafted at all.
Most parents see their player as better than the next guy, when someone tinkers with their stuff to make them better and then they don't, maybe that shows that player is unable to make adjustments in a game that is all about making adjustments.
Son has had more pitching coaches probably than most here. He has learned to take a piece of their advice and use it, which is why he is completely different than he was even on draft day. He doesn't always think its going to help, but he has learned that this game changes everyday, and so must he to survive.
The guy who gets to the big leagues but struggles is sent down to work on why he struggled, that's what they do. If the light bulb doesn;t go off, eventually he won't be on that plane going back and forth between two teams.