Unlike Order, Chaos doesn't get super-awesome walls that can stop an armies advance at all. We get "turrets" (which don't seem to work for me) and frankly, not even juggerknights/giants amount of knockback is enough to stop so many Speartons. I know what you're thinking; "attack them before they can set up" but Chaos does not rely on unit cooperation like Order does; it relies on brute force, which to me means 3 juggerknights can't stand up against 2 archidon and 5 swordwrath, 1 meric/2 speartons, etc.
Tl;dr: How to stop those cheap ones who simply run past your army, killing the fun of watching armies and simply being unfair.