I don't know about the SEC, ACC, Big 12, and Big 10, but the PAC 10 is well-known and oft-played in these parts, and we (meaning Utah and other other top rank MWC teams) just aren't intimidated by them week in and week out.
Regardless of conference, when the mighty fall, they seem to fall hard--witness Nebraska, Washington, Penn State.
For that matter, BYU beat Notre Dame this year, and BYU's program is sucking wind.
I repeat, Utah would not stand up to USC, Cal, Oklahoma, Texas, Texas A&M (maybe), Auburn, Florida, Florida State, Miami, VA Tech, Michigan, Wisconsin, etc. Make Utah play a schedule such as these teams play week end and week out and Utah will not be 11-0. Ain't gonna happen. You can hope all you want to, but it ain't gonna happen. The New Mexico's, Wyoming's, Colorado State's, etc. are not in these other team's leagues. Sorry.