- In the old version, it was more clear to see a relation between the performance and condition loss. now it's more complicate because we have also a new factor, the condition bonus and a difference in abilities.
In training (old version) still you can see the relation between the gaining and condition loss.

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Jeeves- BTW, do you think that the fitness ability of a player/avg of a team, impacts the condition loss of a player/the players in a game?
I do,
I don't. Going back to the old version, it was very common when you bought a scout player, to get injured in the first 4-5 days. And generally 6*-7* players were more vulnerable than low 5* players. Of course their stats (M&P) were much better but this didn't help to less condition loss or less injuries (rather the opposite).
I believe (my personal opinion ofc.) that those "mechanics" are still the same.
* Unless one day a dev come and tell us officially if and how the new abilities has some impact to the game play from now on.

- I agree with Jeeves that it's too difficult and complicate to have some strong evidence from testing and measures so I believe it's better to focus in some more practical things about condition (which has anyway a range between a 18% to 25%).
What I mean ?
- Condition bonus : How affects the condition loss ?
- Playing man to man instead of zonal ?
- Playing high pressing instead of low ?
(the other orders - like hard defending) has no impact