If the TIE Advanced is supposed to be the "Imperial" X-Wing I could see the "Avenger" as simply switching the 2 and 3 from Attack and Hull. Give it a 3/3/2/2 stat line and you've got all the same numbers the X-Wing has and get a ship that hits harder than an A-Wing but takes hits better than an Interceptor even if it isn't quite as maneuverable on the dial.
Well, the TIE Avenger is by no means the Imperial X-wing. It is the ultimate dedicated space superiority fighter, and ate X-wings for breakfast. It saw far less use, but when used, it was frequently an escort for Assault Gunboats.