Remove all arrows. I never play 4-5-1V using arrows, my team fails so hard if I do that. Also check if your players have enough condition and morale. And also check if any of these players in the formation are often getting a rating under 7, if you have such players you should sell them or not use them until the next season/until they are playing better.

I must also say that 4-5-1V doesn't work against every formation.