Well, illegal formation is just a term used for modules that result in severe possession loss. It doesn't mean they can't win, just that the odds are less in their favor. It is pretty ick to be the team they lose to, I grant you. Don't have hard tackling on, don't play too aggressive. This can concede PK...goal, corner...goal. I'd have mentality defensive, really, they are sitting in your end. No counter attack.

Good Luck! Let me know what result