Fmm26 keep starting strong and then losing

Hi, I've been playing fmm26 for a while now and I've noticed a very similar trajectory in all my games. I'll start strong and quite steeply after the middle of the season or in the second season with the same team, I'll start losing heavily.

One example, I was playing with London City Lionesses aiming for mid-table results in WSL. I started particularly strong facing off all the big names (City, MU, Liverpool, Chelsea, Arsenal) in the first 5-6 matches and holding them off well enough to be 4th in WSL. It quickly went downhill after that, starting with struggling with teams like Everton and Leicester, to reaching the point that I were losing heavily from West Ham at home and finishing last place. There were no major differences in lineup between the start and end of season, no loss of morale (everything in the dynamics tab is A/B except loyalty, but that was from the beginning), no heavy injuries, no player exhaustion. I don't get how the same players can hold City at draw in September and lose 3-0 from West Ham in February. I tried many, many different systems without success.

That's just one of many examples. I want to believe that there is logic behind this and I'm just not good at this game, but I really don't understand the huge gap in results with the same players. I've read dozens of guides on tactics etc. but can't seem to overcome this. Any help here?