My guess is that it's probably a pretty simple regression to the mean so the default assumption is that BYU reverts back towards whatever the norm was for us over the past few years. Also worth noting that his system (and most computer algorithm systems) weren't as high on BYU last year.
Last year Sagarin had us at #33.Massey composite had us at #27.
I don't think that's anti-BYU bias so much as how the computers work. In 2020, Sagarin had BYU #5 at season's end, Massey had us at #10.