I should note before starting this would benefit me with Draymond. But I will propose it anyway.
I propose we allow training of current ratings up to their potential regardless of whether a player is all-league or purple potential. Athletic trainings and potential ratings may NOT be raised - so the player doesn't become a bigger monster, he's just able to get to his monster potential faster (or at all, we have seen some purple potential guys never make it to purple current).