Can be the exhausion of running 2 competitive games a day and the resulting lack of training, which is very difficult to recover. I usually won't tolerate any player with three 6 rate in 5 games. Two consecutive 6 should be benched. In such case half a team need to be rotated out.

And that seems to be the reason I've been unable to get into cup or CL final since I can't rotate the whole squad for different competitions, due to the lack of time to play the game.