personally I'm rather pessimistic about this, until the BBs give us a more direct indicator of remaining potential in the player information.
which took me 7 full 2 position ID trainings at the age of 23.
but since it's a softcap it doesn't shut down completely.
Age: 21Height: 6'0" / 183 cmPotential: 6th man Jump Shot: prolific Jump Range: proficientOutside Def.: respectable Handling: awfulDriving: proficient Passing: averageInside Shot: respectable Inside Def.: pitifulRebounding: awful Shot Blocking: atrociousStamina: average Free Throw: mediocre Experience: pitiful