I've never seen a player, in the history of baseball, who had his career altered by moving him too slowly. But I have seen players whose careers were altered by moving them too quickly. And that is something you have to be careful about.
"If you move a player too quickly, you can put a player in survival mode. You can see a guy start swinging at every first pitch or a pitcher throwing a lot of breaking balls. They get outside of development mode and go into survival mode if you move players too quickly. But the large percentage of these decisions are made based on a player's mental toughness."