Ashbringer worked great for me my second season with Southampton, finished 7th. Same tactic and i am in 17th after 14 games and being destroyed by other teams now. Didnt change anything, not sure whats happened
The AI adapts to the opponent. At least according to some of the feature videos on the game. Meaning you will have to adapt also. Plug and play tactics are more difficult to set up than in previous versions. Of course other factors could play a part in your bad run such as morale, lack of leaders, low determination etc.