Losing a Game Doesn’t Mean Much if There is a Resume
Last year North Carolina was ranked No. 19 in the first CFP poll before losing to Notre Dame by two touchdowns. The next week they rose in the rankings by two spots to No. 17. Essentially the committee saw North Carolina as the 19th best team before the game, and when the Tarheels played better than expected against Notre Dame, the committee felt they were the 17th best team.
While examples like this are a bit more rare, the committee does for the most part stick with their rankings after a loss normally only dropping a team three to four spots whereas the AP poll is a bit more unforgiving often dropping teams more in the seven to eight spot range.
In other words, if a team is supposed to win by ten points and they only win by two, it would have been better for them to be favored to win by one and end up losing by one.
For teams like BYU last year, without much of a resume, the one time they lost they dropped further than any other team ever would. This year, with their resume, with the same kind of loss (Top 20 team), the Cougars would likely only drop two or three spots.