Funky stuff with charging. I've had cases where my perfectly formed formation charges towards the AI who are in some horribly whack formation with a lone guy far out front. My formation proceeds to bend around that one guy like a rubber band and not perform a proper charge, then getting slaughtered.

I found that funkified formation can mess up charges and now place in front of my lines a couple of spear units 2 deep and in loose. Destroys cav charges every time.