They completely ignore that BYU has seen losing records before, even with a very well pedigreed coach. They also ignore that by definition, half of all coaches have a losing record against D1 schools each year. Throw in the fact that BYU has a limited recruiting pool which historically ranks about the middle of the pack in D1, you can see that BYU is walking a razors edge and could easily start seeing losing records again.
This feels a lot like Utah basketball. Utah started rolling the dice with basketball coaches and their program went into the tank for almost a decade. BYU has had success in the past, but that doesn't mean that coaches are plug and play and you'll get the same result as you have historically (just ask Utah).