Im playing Seleucids atm. The AI has the right idea against my Phalanxes. Its actually funny. Usually im heavily outnumbered by eastern infantry, and they will just attack my flanks totally avoiding the center. I of course have totally adjusted to this tactic and I now have 2 to 4 units of Cataphracts on the wings waiting for this mad rush to my flanks. I imagine the AI attempts to get around that semi hedgehog by using archers if it has it and sending its infantry to the "flanks" it may have trouble finding the flanks in that setup however ;p