99% of teams lose at least once. 98% lose at least twice. 96%+ lose more than twice. It is part of the randomness of sports. Of the 10 teams with better records than BYU this year:
Indiana has zero wins against teams with more than 6 wins
Army has 1 win against a team that doesn't have a losing record. Was destroyed by the only team they played in the top 50
Texas has no wins against top 50 teams and only 1 win against a team with more than 6 wins (CSU)
Penn St. has 1 top 25 team (literally ranked 25) and the rest no other wins against top 50 teams, 2 teams with more than 6 wins, including Bowling Green as the 2nd.
Miami has no ranked wins. Only 2 wins over teams with 7 or more wins.
aTm has 1 win over a team with 7 or more wins.

So only 4 of the teams with a better record than BYU have EITHER (BYU has both) a win over a top 10 team or 3 or more wins against teams with 7 or more wins. All 3 of BYUs wins over teams with 7 or more wins are P4 teams with 7 or more wins.