The sidesteping. Well that..I dont know if its buged or the programmers intended to do it that way, but the best soldiers in a phalanx where to the right flank. A rare but a historical tactic was to bring the right flank close to the enemies left and the left phalanx flank to try to keep away the enemies right.

So the best swarriors would engage the enemy and the worst just keep him at bay.

I would think that its a bug if when 2 phalanxes engage and slowly try to do this to eachother.