Why do players' Ability progression fluctuate?

[Ron Wandle]

Why does the Ability graph go up and down, when it isn't related to age, injury, unhappiness or playing time?

For example, this guy, who's 26 years-old, plays regularly, hasn't been injured and doesn't have happiness problems:

[kingjericho]

Because that's what happens IRL, sometimes players don't develop as expected even though they are playing.

Harry Maguire wasn't injured when he signed for Man Utd yet the team didn't fit his style so he suffered from it and he was unable to keep his good form from the Leicester days.

[kertiek]

not only that , now fatigue and jadeness changes the player progression, if suddenly a good player starts going downhill, is time to start rotating him and giving him a few rest days, after he lowers his fatigue levels he will start going up in his "progression" and being able to perform at his "full" CA.

i feel in previous years progression was a representation of current ability only but now is more like his current performing capacity with more factors affecting it.

Edited December 3, 2022 by kertiek