3n-4-1-2 that changes to 3n-2-3w (am)-2 in game. Any suggestions how to counter that?

I have an opponent that starts the game with 3N-4-1-2. If he is scored upon, he changes the formation to 3N-2(MC's)-3W (AML-AMC-AMR)-2. Although that would seem like a system that is dangerously attacking and dangerously vulnerable in defence, it doesn't matter. Tha power he gets from 5 people (3 AM's and 2 ST) attacking overwhelms anything i have tried. Anyone with any ideas on how to counter something like that.
Oh, and when he changes to that system, he doesn't even put blue arrows on the 2 MC's. Full Attack. 17-1-0 in league. Seems noone can counter him.
So what do the brightest (and this is not sarcasm) minds of the game propose?

Thanks in advance

Yeap... just like me... clueless...
it's ok i guess. It's just one of those systems...