You are funny guys... You didn't even ask why I bought new 11 players.. Maybe because the players that I had on the bench were in optimal moment to sell like 59%, like 39%, like 79%..
you see, there are too many info that any manager (except you) doesn't know.
If you asked about a specific game, why you lost from a much weaker team, giving some details, we could have a more specific answer.
But generally why your team is loosing/ not performing well, difficult to be answered.
Too many unknown for us factors.

Anyway, a common tactic is to loose this season and try to re-group.