If Ohio State and Michigan play each other on the last day of the season
And Ohio State and Michigan are ranked #1 and #2 when they play, then why isn't that the game to decide the National Champion?
It's the end of the season (because college football shouldn't be played after Thanksgiving, and at least the Big Ten knows that).
It's the #1 and #2 teams against each other, putting it all on the line for the title of best team in the nation.
It's mythical anyway, so why not this game rather than another mythical game two months later?
None of the other options — neither the Big East undefeated that isn't yet nor the one-loss teams that are clearly not as good as whomever beat them already — are as good as Michigan or Ohio State.
So why isn't the national champion going to be crowned on Nov. 18th?
(This is also known as, "How the BCS fucked up college football again.")