Say BYU is 12-0 after CCG week, and Wisconsin just won the Big 12 CCG, finishing only with a loss to BYU; and Washington just won the PAC 12 CCG game, finishing with only a loss to BYU.
How many points would BYU have to have beaten them by to keep the conversation from stopping at "Well that was at the beginning of the season and if they played now BYU would probably lose. Gotta take the best teams right now and that's Wisconsin and Washington". Even though BYU beat two top 5 teams, I could see that being the argument against them.
Based on how playoff selection has gone in the past, head to head matchups haven't always favored the winning team, and I think the only way BYU makes it in the playoff is if they CRUSHED everyone, not just beat them.