Earned rank is a season quality ranking, not a team quality ranking. But it's certainly defensible that we've had the highest quality season so far, especially by the earned rank method (difference in W-L from the average of all D1A teams playing the same schedule). Here's the other 4-0 teams:

Alabama (WVU [Atlanta], FAU, SMiss, Florida)
Arizona (UNLV, @UTSA, Nevada, Cal)
Duke (elon, @Troy, Kansas, Tulane)
Ga Tech (wofford, @Tulane, Ga Southern, @Va Tech)
Marshall (@Miami-OH, rhode island, Ohio, @Akron)
Miss State (SMiss, UAB, @SAlabama, @LSU)
Nebraska (FAU, mcneese st, @Fresno, Miami-FL)
NCSU (Ga Southern, Old Dominion, @USF, presbyterian)
Oklahoma (La Tech, @Tulsa, Tennessee, @WVU)
Oregon (south dakota, Mich St, Wyoming, @Wash St)
Penn St (UCF [Ireland], Akron, @Rutgers, UMass)
Texas A&M (@South Carolina, lamar, Rice, @SMU)
Washington (@Hawaii, e wash, Illinois, Georgia State)

Florida State will certainly pass us next week if they beat NCSU to go to 4-0.