I think this thread and the one on whether scouts care if you toil in "a bad program" come down to the same point — does a kid have the mental fortitude to inspire himself to be his best, despite not getting all the playing time he wants, despite being in a bad program, and I'll go ahead and add, working with a coach he may not like?
There are lots of ways to learn to play baseball and to keep getting better.
But having the mental attitude that you will give your best even when it's hard, is tough. It's within yourself, it's something you have to do for yourself and I think it's a hard skill to learn, and probably almost impossible to teach.
Those who don't have that mental strength quit and probably should. Those who do have it, play on.