Well, I'm on my fifth season and been using the same tactic for that stretch. On my first four seasons, I only lost twice both on single goal margin. Currently on my fifth season, I already have two defeats - 1-2 against Madrid and an unacceptable 0-2 against Betis, snapping my 170+ undefeated streak. Moreover, I have more games which ended on a draw, more games where we conceded at least 1 goal, and more games where we have to fight back from 1 goal down. I haven't made any transfers before the start of my fifth season as I have an excess of young quality players.
At first I was thinking if it was due to the fact that I accidentally chosen minimum size of pitch which doesn't suit my team/tactic who plays wide and maximizes wingers and fullbacks. But I was getting mixed results at home. Sometimes I won by rout, sometimes its close, sometimes its draw. But not a lost.
I started tweaking the tactic, adding swapping among my wingers and strikers particularly, and I started winning and dominating again. What do you think