First off, the fact that the battle means that something is very off, it's not the damage that the at's do because again, there would be fewer rounds. So the only logical explanation would be techs. As to the issue of arch bows not hitting pure archers, that is just the way it works, defending units get a wall bonus so the defending archers outrange the attackers. Plain and simple, you don't try to kill 200k archers with an arch bow, it's been that way since I stRtwd playing and I've never seen a report with an arch bow taking out a city full of archers. So Im inclined to think it's been that way for quite a while. A city with 200k archers is not invincible, but you have to know how to use the right tools.