It's bullshit because the SEC also-rans - South Carolina, Georgia, etc. - get their rankings artifically inflated, which only serves to ensure that at least one SEC team stays in the national title hunt.
Oh, Alabama lost to South Carolina? Oh, well, that's because South Carolina is sooooo good - I mean, look, they are the SEVENTH BEST TEAM IN ALL OF COLLEGE FOOTBALL. So, Alabama, let's see, you'll drop to #5 in the polls, and South Carolina, you're now #3.
Fucking puke.