Big East used to be a power conference. They aren't anymore. While relegation isn't a thing, there is movement among what teams are in power conferences and which conferences are power conferences.
Heck, Temple was even kicked OUT of the Big East for sucking.
Conferences can move up and down the totem pole, but you need consistent poor performance. One year of sucking isn't going to do that, and while I know a lot of you guys hate the Big 12, the reality is that they've been easily better than the Pac 12 at least for a while now and aren't far behind the Big Ten or ACC top to bottom.