Why do you think Derke fell off? Like from being best player contender for two years to getting carried now , loosing 1v1s pretty frequently
I wouldn't say he fell off; he just doesn't get the same help he used to. In his finals, he got 21 FK and 19 FD, but that's his job to create space and die in a favorable spot so he can be traded for a 4v4 post plant, but now his play doesn't reflect in Fnatic's results because they been so mid all year which leads people to think he is worse than he actually is.
They might just have gotten burned out and practiced less as a result, but it's clear that their peak was during lockin and masters last year. They lost steam during the previous year's champions and remained that way until this split's playoffs, where they showed signs of returning to form. I can't tell you unless Boaster or someone on the team gives clear information about what's going on with the team's mental and such.