If Clem, OSU, OU and SEC champ are undefeated, that is your playoff. ND cannot be undefeated anymore and the PAC is out. SEC cannot get 2 teams in if the other schools are undefeated.
If Clem loses a game, SEC champ has a loss Big undefeated and Big 12 undefeated - Clem is out and 2 SEC teams are in.
Worst Chaos is if Clem, OSU, OU and SEC champ all have a loss. SEC likely gets 2 teams in. The next 2 are a battle. It comes down to who they lost too. If OSU lays an egg against Rutgers then it does not matter, they are out. If OU loses to say WEst Virginia or Baylor, they are out. If OSU loses to Penn State or Wisconsin (early) and beats them in a rematch, it could play differently.
Clemson losing to anyone will really hurt them, however, they may pass the eye test which apparently hurt the Bucks the last 2 years. To be honest, they did not pass the eye test then and the last time they did was 2016. The ACC is so weak Clemson is not challenged this year, but they also have the 5 star talent of Bama. Does the committee punish them because they did not get the job done despite their talent? I hope so.
They need to do something to address the weakness of the ACC and how you can skate through the schedule there. Clemson has benefited from it for the last 5 years now. FSU was the recipient for many years before that. People may knock the BIG as top heavy, but at least the top 3-4 teams are all top 10, top 15 teams. In the case of the ACC you have 1 top 25 team 2 tops