and extra points after an offensive touchdown as offense), which would put them at 4th in the B12.

But other teams have defensive and special team points too. I checked Texas Tech's 137, and they had a pick 6 against Cinci, so that would bring them down to BYU's 130 (so BYU is at least tied for 3rd, maybe even better).

I think the best argument you could make to say BYU's offense isn't top tier is to say that BYU's 4 opponents have had worse defenses, but it's too early in the season to make that argument.