It sucks, but some ilegal formations are really tought to beat.
I had one game were the other manager only had dr DMC and dl in the back, i was playing with 2 ST in the meadle but only scored at minute 80 from free kick.
The players can move over the field, whend you are seeing the coments you often see your ST helping in the back. The reason is simple If you can not put the ball in front, you are always being pressed, it a suicidal tactic, but sometimes with this engine works.