Having access to the functionality of the keyboard arrow keys to shift formations fowards, backwards or sideways been a blessing in disguise for commanding phalanxes. Never has marching a nigh impenetrable wall of spears into the face of the enemy battle line been easier.
For all the foibles of the battle AI, you have to admit that they still have one very specific leg up over the more recent Total War games. They can actually conduct a tactical retreat from the battlefield if they sense the situation does not favour them fighting it out. Sometimes discretion is the better part of valour and the AI is not afraid to live to fight another day, where the terms of battle might be more favourable.