Have the AI Focus More on build Archer/Missle Units
If the ai would build more archer/missle units then it wouldn't so often fall prey to the first strike in melee advantage humans take. Also if the AI is the defender force the human player to move forward not the ai unless the human player has an abundance of missle/archer units. It should be known to the ai the missle/melee advantage the human player has when the combat sequence begins. So roughly a preliminary battle should be played out in the ai's head (like wargames before the Normandy invasion) and given at least 3 choices on how to fight the battle out in the best advantage of he ai.