While it is a different strategy and way of playing 40k, Fritz' Null Deployment reminds me of the way my friend Andrew plays his Tyranids, admittedly without mawlocs. While I have not had a chance to test out this strategy, I think I've got a way for most armies to defeat this new strategy.
There is an old saying that asserts no plan ever survived contact with the enemy. This is usually the case when each player has his (or her) own plan and tries to play it out to the end, for good or bad. I suggest you adapt your plan and instead of trying to do what your army wants to do, do what your opponent doesn't want you to.
Fritz likes to play with his opponent's head and this is a good example of it. This is an example where Fritz is presenting a bad choice as a good choice. The bad choice in this case is to move away from the wedge and toward the board edges. The good choice seems like a bad choice, but is better than the alternative: hit the wedge head on.
If you stay toward the middle of the board you will have to face the wedge, but this is not as large a force as the outflanking units. You will still have to deal with the deep striking units, but you will have at least one turn you will not have to worry about them. During that turn (don't bet on having two turns free with a Hive Commander and/or Lictor) focus your fire on the biggest threat to your army be it the MCs or gaunts your opponent starts on the table as his/her wedge force. The wedge is supposed to scare you to the edge where the real threat is, don't let it.
Bring all of your firepower to bear on your opponent's wedge force, you should have a good chance of weakening it or destroying it in the turn or two you have before the reinforcements show up. The wedge should only comprise forty or so percent of your opponent's army. You can fight a portion of your opponent's army with all of yours and keep a distance between you and the outflankers, who are generally looking to charge you. If you can keep from being assaulted by the outflankers, you can decide how you want to deal with them.
I must not fear.
Fear is the mind-killer.
Fear is the little-death that brings total obliteration.
I will face my fear.
I will permit it to pass over me and through me.
And when it has gone past I will turn the inner eye to see its path.
Where the fear has gone there will be nothing.
Only I will remain.
-- Bene Gesserit hymn against fear