QB switch so as such, that loss is being discounted and one of the reasons why they ignored the head-to-head result between the 2 schools (kind of one of those "we think if they played now that Utah would win" sorts of claims).

It's being referred to as a coaching mistake because unlike the reasonable take that the committee would discount a loss because a key player was injured during the game, in this case the committee is discounting a loss because a key player wasn't played due to a coaching decision to not have them start early in the year.