Don't matter the settings, yet again, be it 1v1 fights or an entire army, the AI cannot cope with you circling them continuously. Duels you'll land ever hit and murder them, simply by circle strafing and if you have the patience and enough archers, circle strafe their entire infantry line/s and you'll easily dominate battles in which you're outnumbered 3/4 to 1
Not sure how to fix it in 1 v 1's but surely for field battles the AI focusing on 1 man on a horse, whilst being mowed down under constant archer volley fire is easily fixable. Just have the AI ignore you for the greater threat