I played vs #1 in league today for first place and I won 1-0, BUT

I played for 75% of the game with 80/20 possession because of a possible illegal formation?



He changed the DML to a ST at the 75% mark of the game and the 80% possession for me started to go down and eventually got to 70% by the end of the game.

Is having 3 on any wing an illegal formation?