In the last 50 years:

BYU is 3-37-1 vs top tier P5s (P5s that finish with 9 wins or more)

BYU is 32-33 vs 6-8 win P5s

BYU is 29-16 vs. 5 win or less P5s

Since 1990 BYU is 17-41 vs FBS non P5 teams that win 9 games or more. Boise has won 9 games or more in 18 out of the last 20 years. BYU is 2-7 vs Boise when they win 9 games or more.

So in a typical year:

Top end P5 is a loss

3 mid tier P5 is 1-2 if only 1 home game. 2-1 if there are 2 or more.

Utah and Boise are probable losses. Two lower end P5s are probable wins. The Boise, Utah, 2 lower end P5 is 2-2 for BYU the majority of the time.

Top end G5 is a likely loss if 9+ win caliber. The other G5s plus FCS are almost certain wins.

6-6 to 7-5 will be typical. Really good BYU teams will be 8-4. 5-7 could happen if unlucky with the schedule. It could be worse than 5-7 if BYU is truly terrible. We’ve seen that.

BYU would have to be better than they have ever been if we are hoping for things like playoffs and NY6 bowls.