You either accept that BYU is an AAC level team and move into the conference, or you replace BM with someone who will take you to the higher level.
BYU took a big gamble leaving the MWC, and BM responded by dropping a level. Other than the 1st year of Indy, with its WAC-heavy schedule, BYU has gone 8-5 since announcing Indy status. I don't think BYU moved to Indy to become the next Army. Even Navy left Indy and ND is mostly in the ACC.
BM isn't making it easy. He isn't terrible, but he isn't great. One of 3 things will happen over the next few years: BM will drop even further and get fired; BYU will accept that it is a mid-major and join the AAC; or BYU hired a new coach to try to get to the level. BYU just cannot stay 8-5 forever and remain Indy, and I just don't see BM bringing home an 11 win season against this level of opponents.