Help me understand what are the reasonable occurrences that *should* prevent BYU from going to the playoff this year? (Thinking more in regards to standing rather than "Tayson blows a knee" or "Referees actually start calling 'targeting' on BYU LBs and DBs")

Examples:
Two losses? One loss? Undefeated team in all or 4 of the P5 conferences? Post-regular season (pre-bowl season) SOS has to be below (y) if (x) amount of loses?