Compared to the NHL, the Buzzerbeater players seem to have a much shorter effective career. Some of the top tier players in the NHL are past their mid thirties. Think of Pronger, Lidstrom (with his 60 point season at the age of 41), St Louis (99 points), Selanne or Recchi. 3 of those are even over 40! Are you going to watch Jagr's comeback?
In BB though, you would reach an all star potential cap only after 5 seasons of training and your value on the transfer list seems to drop heavily when nearing the age of 30. At the moment, it feels like unless you acquire a trainee, the value of any other player can only drop after you buy him off the transfer list. But of course, this game is only in its 17 season. The oldest player that were drafted and trained properly would be 35, 36 year old now. We're only seeing the first batch of well trained mid 30s player.