So if the 8-team playoff happened this year, and we use p5 champions plus 3 at-large (which seems to be the popular opinion). The eight teams would be:
conference champs:
1. USC (pac12 champ)
2. Georgia (SEC champ)
3. Ohio State (Big10 champ)
4. Oklahoma (Big12 champ)
5. Clemson (ACC champ)
Now if we disqualify any of the losing conference championship teams (Stanford, Auburn, Wisconsin, TCU, Miami) and you go by the CFP rankings (http://www.espn.com/college-football/rankings/_/poll/21/week/15/year/2017/seasontype/2)
The 3 at-large bids would go to:
6. Alabama
7. Penn State
8. Washington
UCF would have been next in line after Washington bud sadly would have missed out even with this system.