It would be nice if there was not a fixed PA.
For example: Fabio Coentrao had a low PA. But he had two very good seasons at Benfica and ended up at Real Madrid, and FM had to change his PA.
Same as Falcao, he had a low PA. But again played two great seasons with Porto and now he has a very high PA/CA.
Because the way the game is now, it's like it's not worth giving opportunities to player's that don't have good PA because you know they will never get much better (while reality show's that this is not allways the case)