They beat Rice, who is 0-3 and lost to Old Dominion.
They beat Michigan, who is 2-2 with wins against Appalachian State and Miami (OH), and a loss at home to Utah.
They beat Purdue, who is 2-2 with a 21-point lost to Central Michigan.
Has Notre Dame looked particularly impressive in those wins? I don't think so... I guess the difference between BYU and Notre Dame is that Notre Dame will at least get a chance to prove it's ranking later in the season against Stanford, Florida State, and Arizona State.