you could argue that the offense bears more responsibility for the losses than the D, I’d buy that.
But I think the main point of the OP was that ASFP (determined in large part by the soft defense) has had a significant effect on offensive productivity.
I agree with the OP that BYU’s D has had far too many series where they’ve allowed 3 or 4 first downs, and though not allowing the opponent to score, they’ve allowed the offense to get pinned back deep in their own territory.
That, along with the fact that giving up longer drives burns clock and limits offensive possessions, have both had a dramatic impact for sure.