If you can't win your conference, SOS would be the determining factor of getting in. The best way to do that is by scheduling quality OOC teams. Playing Citadel, or the like, doesn't help anymore while playing UCF, or ND, does. Washington State would be better off playing UCF (than EWU or SJSU) because a win would really boost their ranking and a loss wouldn't hurt them.
Perfect example this year is Michigan where losses to OSU and ND would almost ensure that they are one of the top 8 over virtually any other school including a 13-0 UCF who plays virtually nobody. In addition, UCF, or other teams with like ambitions, would have an easier time scheduling high quality Power5 teams because a loss to UCF wouldn't doom a team to being left out if they didn't win the conference as well as gain them some credibility even in a 'quality' loss. Just like a 10-2 Michigan ought to be a shoo in, any other team that had two losses if one of those losses was to a 13-0 UCF would have a strong argument to be left in.