I think we have little influence on the game, the results seem to be random, and ball possession is not even worth taking into account.
Tactics? Win bonus? Team quality? I don't believe they have any influence at all.
My second team on which I spend 5 minutes a day, a mixture of 1-3 stars players, dominates 5 stars teams in the cup and CL.
My main team, which is quite good, struggles with 10 level weaker teams...
Anyway, I'm waiting for any change in the game mechanisms.