I just played the CL final where I was +16%. Was 2-0 up after 15', opponent scored on two consecutive set pieces. Score was 2-2 at halftime and my GK (130%) and 2 DCs (almost mutants) had ratings below 5,4. Switched formation and tactics to drastically change the conditions. Scored 4 and won 6-2.
I guess you need to fundamentally shock the game engine to turn things in your favour. I went from 4141 to 32212 with DML/DMR and 2 second strikers upfront and high pressing, short passes, focus to middle, hard tackling, instead of low press, mixed passes, focus down the flanks, easy tackles.