In my last experiences, fielding an army which has enough pikes to stretch over all the main frontline (even only 3 ranks deep) completely unbalance the battle toward the human, since only flanking forces will not jump head first on your pikes, and if you present some anti-flanking units on your own flanks/rear they cant combo break you. Then of course there is some situations where the AI can still win (very heavy cavalry, lots of nice ranged, overwhelming numbers, a much better general, etc...) but its still pretty OP.