I think the feeling of superiority comes from head to head experience with those teams we spent decades (WAC/MWC inclusive) in a conference with that are now part of the MWC...
W-L Opponent
24-7 Air Force
39-27 Colorado State
5-5 Fresno State
21-8 Hawaii
16-3 Nevada-Las Vegas
45-14 New Mexico
28-7 San Diego State
7-10 San Jose State
44-30 Wyoming
That is 258-118 against our former WAC/MWC and now current MWC foes. That would be where thoughts of superiority come from...
Below are teams that BYU did not spend time in the WAC or MWC with but have played.
2-4 Boise State
5-3 Nevada
47-35 Utah State