Oh, I agree, 4-3-1-2 with sarrows can completely confuse defense, sometime fullbacks don't know what to do - mark strikers, close them down, the DCs find themselves by the sideline, and one of those MCs (and that is assuming that u have AMC covered) just sneaks in completely unmarked. That's true, this strategy can make chaos too. Luckily, it's not that common.
What hurts most is that, even when I carefully design defense against these strategies, usually I forget something, and the punishment is an almost certain goal. On the other hand, too many specific requirements can have a negative impact, since the football players (especially defense) are not too bright for so many informations

Anyway, I'm talking too much and instead, I should try with your advise. Will let you know, thanks!