Almost the reverse of the Semien situation where a 6th rounder was projected by numerous scouts to be tapped out projection or potential-wise/utility or fringe AAAA...until he found someone in another organization who really believed in him as a player and invested so much personal time in his development.
Tatis, they simply got outscouted on what possible range of outcomes they had on their hands from the Padres having 3x the amount of Latin American coverage...and investing time in stalking the back fields.