2% of these guys reach the big leagues (Vladdy, Soto, Acuna, Eloy, Tatis, Franco, Devers, Mazara). These guys already have a lot of baseball in their pockets, they're playing baseball since they are 7 or 8 years old.
They are a good bet, since they are young and the teams can teach them what they still need to become in good players, spending little money.