Simple answer for a very complex question; there is no answer. Consider Sean Burroughs - he had the genes, but not the power. Dewon Brazelton had the pitches, but not the mentality. Mark Prior has the talent, but not the luck. It's not because the players don't have the talent to play at the big league level. Instead the detracting factor is usually out of the player's hands. The likelihood that a prospect booms or bust is pretty random and not something we can project with any amount of credibility. Something far more predictable is the player will receive numerous opportunities.