the bad thing for Terran... that was only 2/3 of the army...
Well, yeah, that wasn't even half of Terran's.
Our rustiness is on the organizational/follow orders and be where you need to be side of things. Everyone is used to just doing whatever they want and most individual Lords deal with monsters in their region pretty much by themselves, maybe with help of a neighbor or anyone who is passing by. They aren't used to following movement orders to much.