When the PAC teams only play PAC teams, nobody can make any data-based claim that the PAC is good.
Utah did play 3 FBS games outside the PAC, and lost two of them (one an absolute blowout). They lost both P4 games, as they have done every P4 game since 2017.
So I don't think the data backs up any claim that winning the PAC or beating USC is an accomplishment.