I've noticed that the player potential becomes insignificant at about age 29. If you go to the manage roster option and choose view card on any player thier stats, bio, chemistry, etc comes up. When you get to the screen that shows the players skills in a hexagon you will notice players above 29 years of age don't have significant potential (it is basicly not a factor any more). Players younger than 29 still do.
I'm playing association mode in 2k10 not sure if this is the same for season mode or any mode in 2k11. It is very interesting. I think players potential is a rate of how fast each player can progress. I've noticed that a player with higher potential can improve faster. (As of right now I also think it means that if put in the wrong circumstances, a players skills can decrease faster i.e. lack of minutes if the player is a big minute player, extended losing streak, or is becoming unhappy). But that last statement could be wrong, and it may just be something I'm experiencing.
So what does this mean for older players?
It's not all about the players ratings, potential affects trades also. So I'm assuming that 2k has some what of a system that says if a player is younger his potential will be greater and it decreases as the player ages. The rating of the potential will not decrease but it's value will
For instance you have a trade and a team is evaluating 2 players on your team.
Player A: age 20 overall 73 potential 81 (sf/sg)
Player B: age 32 overall 71 potential 89 (sg/sf)
If we disregard all other ratings (assume they are all the same, and the 2 player only reason for different overalls is because of position) the computer is more likely to take the younger guy. Potential doesn't play a big role in individual games but throughout a season, association, and in trade is when you see the true value of potiental