2021 looks great - 3 potential top 25 P5s (USC, ASU, Utah), 3 other respectable, not great P5s (Virginia, Baylor, Wash St), a terrible P5 (Arizona), a top G5 (Boise St), some typical lower-end G5 (Utah State, Georgia Southern, USF) and a FCS team (Idaho St). That's not quite a P5 schedule, but it's pretty close.

2019 though was a lot different. 1 top 25 P5 (Utah) who blew BYU out, 3 mediocre to respectable P5s (USC, Washington, Tennessee), Boise St and a schedule full of chaff.

If 2021 is typical, yeah, that's impressive - if it's 2019, then it's probably not enough.

So a typical indy schedule (excluding 2020 for obvious reasons) looks like 1.4 ranked P5s, 0.8 ranked G5s, 2.5 mediocre P5s, 0.9 terrible P5s, 5.4 run-of-the-mill G5 teams and 1 FCS team.

If BYU goes 11-1 against that schedule (losing to their only ranked P5 opponent) they're probably not a playoff team.  If they go 11-1 against the 2021 schedule, they probably are.

Over the last 5 (non-2020 years), BYU has managed to bump it up though, basically replacing half a run-of-the-mill G5 game with a ranked P5 opponent for each season.  So 11-1 against that "average" schedule would give them two top 25 wins (one P5, one G5), as well as a top 25 (P5) loss, and another 3 victories against bad to mediocre P5s.  My guess is 11-1 against that kind of schedule that puts BYU right on the border.

EDITED to reflect Utah 2021 as a non-top 25 team based on https://www.espn.com/college-football/story/_/id/31366880/college-football-post-spring-top-25-power-rankings