Fitness does matter in this FM, but in 21 this was true, you slap a gegenpress system on any team with the most unfit players possible and they would act like if they were powerhouses. But its not that simple, I use a 4-4-2 where I protect the middle with my life, 2 pressing forwards, one BWM paired with a B2B, sometimes pairing 2 BWM and 2 quick and strong CBs. Sometimes I concede in long balls to the back of my full backs, but thats a risk i'll take