As long as the FBS National Championship playoffs are capped at 4 teams, at least one Power-5 conference is going to be frozen out. In the first year, it was the Big XII; this year, its the Pac-12, and Stanford. The Cardinal were the first out of the top 4.
Clemson, as the only undefeated FBS team, after defeating North Carolina 45-37 in the ACC Championship game, got the top seed, and will head to the Orange Bowl on New Year's Eve
They will meet Oklahoma, the champion of the Big XII. The Sooners were destroyed by the Tigers 40-6 last year in the Russell Athletic Bowl, but got not only the benefit of last year's snub of the Big XII conference, but also the attempt of the committee to create what would be the best ratings driving matchup in the championship game, which would be Alabama-Oklahoma.