When it looked like So. Miss wasn't going to be bowl eligible, I think they put out the word that they were NOT interested in trying to find a 12th game, mainly because they had had a lot of injuries over the course of the season. Now that they manage to get a 6th win, without benefit of another game, I guess they changed their tune and decided to go to a bowl, if invited.
Also, I believe in recent years CUSA has picked off a bowl slot or so whenever a Power league, or leagues, couldn't fill all their tie in bowl slots with eligible teams.