ND gets their bellybutton handed to them every year if they make it to the playoffs lol
They got stomped, but it's not just them. The team getting stomped is (other than 2015) usually any team playing Clemson or Alabama.
2015: Oregon stomped FSU; Ohio State stomped Oregon. <--- the outlier
2016: Clemson stomped Oklahoma; Alabama stomped Michigan State.
2017: Clemson stomped Ohio State; Alabama stomped Washington.
2018: Alabama stomped Clemson.
2019: Clemson stomped Notre Dame; Clemson stomped Alabama.
But yes, rankings are not the best measure of how good a team is because rankings are based mainly on record and not much on anything else (such as strength of schedule, "eye test", etc.) regardless what the CFP committee says. Things other than record matter mainly when two teams have the same record, and the other things are used as a tie breaker.
I'd like a rankings system based on more than record -- some sort of Elo system or math-based system that significantly takes into account opponents and game scores.
That's what SP+ and FPI do, but they are complicated models.
I'm sure there's something simpler that would get us most of the way there and be a great improvement over ranking based nearly only on record.