So we just ignore Harper and Rendon and Strasburg and Soto and Turner?
Harper, Rendon, and Strasburg we're pretty complete players before making the bigs. They were all "fast to the majors" with "advanced approaches". Turner was only in the Nats minor system for like half a season before he was called up. Turner was also a quick prospect when he was selected by the Padres.
I don't know if Soto actually came hatched from a baseball that was sired by Ted Williams, but honestly he seems like the type of guy that isn't really a product of good development. Maybe he is, but literally he is maybe the only exception to the Nats development turning out high quality players.
