All these kids have promise....until they don't.
Because of ample supply, most teams really don't go out of their way to develop them. They either conform and perform to whatever benchmarks are set, or not.
I have met too many kids under 20 with TJ scars because throwing 90-92 doesn't cut it. So they take the gamble, what else are they going to do? These kids were the jocks and stars in high school, not too many planned on a back up career.