Strength of schedule analysis usually focuses on how many wins your opponents have, not the types of opponents or games that you play or that your opponents play.

MWC and WAC BYU played most of their games against opponents that they had out-recruited and out-sized. BYU built its program by beating UNLV, New Mexico, Wyoming, SDSU, UTEP, etc. And these teams all played each other too. So, yes, Utah, Colorado St. and Air Force would have some good teams once in a while, but BYU was king of the castle and had better talent. Several times BYU started the season 1-2 or 1-3 after facing mid-P5-level opponents and then rolled through the MWC schedule.

Independent BYU has played way more opponents that outperform BYU in recruiting and have more athletes, deeper rosters, and better talent; especially early season. When you go up against bigger and better athletes in the early season, it takes its toll. Players get beat up and the depth chart gets tested...It's similar to what happened to Utah after joining the PAC. They went from 10+ win seasons to losing records in the PAC. It took Utah 4 years to even get to a 5-4 PAC record. They had to build depth before they started to contend in the PAC. BYU is going through a similar process. Note that BYU is going after more athletes with better measurables to try to improve athleticism and ability to compete against those tough September schedules and still continue to win games as the season wears on.