Were you watching the match, or looking at statistics after? I've looked at games that showed a player with 4-4-2 20% possession, so there's something else going on there - I'd speculate that they had red cards/injuries and didn't have subs set.. - e.g. maybe the DL was injured so he had a 10-man formation with no left flanker or something like that.
How about this: "Some combination of 3 Defenders (3 players anywhere in the back row - GREEN icons)"?
I'm confused with your comments on midfielders. Are you saying "at least 3 midfielders (DM*, M*, AM*) one of which has to be in the middle row (MC, ML or MR)"?
No, no. Not asking for ALL illegal formations, just examples that don't fit the (definitely) known criteria. So no need to show a formation with only 2 defensemen or no strikers, because we already know why those are illegal.
Jay, I don't know. But it's part of Top Eleven, and nobody knows exactly what the criteria are.