More people are playing Buzzerbeater now. The change of TL prices can be from many many variables. Not saying which are involved but examples could be:
1) There are certain lulls in the season in which players are worth less and other times when they spike higher, ie ASB and just before the playoffs.
2)A 30k center could be due to the fact he is monoskilled and now deemed less valuable.
3)There are alot more similar players to the one you mention thus more supply to the same demand = a lower price.
These are just a few variables all of which can factor in different amounts. The point is its not just how many people play the game.