Make it simple: Training makes the different in this game. Potential could change if players are being trained almost to the cap. BB could review or update the potential during new season.
That is not simplyfing things, that complexifying it. "You have a potential, but it can change, maybe possibly".
Mayo and Arenas (who was more a star for Washington than GSW) are already happening in BB. That guy, (31690797), for example seems unlikely to fullfill his MVP potential while on the other hand some some PA or Superstar capped will be extremely important for their teams.
If this is the case, then BB could lower down the potential from MVP to superstar at the age of 24 or similar. On other hands, some PA or superstar were trained almost to the cap at the age of 22~23, then let's raise the potential to MVP.
90% players should remain the same potential, maybe just update 10% players (5% potential will be lowered down; 5% potential will go up). Let's see whether BB managers like it or not.