I think a good comparison for how prior year performance is impacting BYU in prior rankings right now is SP+. BYU is #35 overall in SP+. However, when looking at "Resume SP+", they are #9. Colley's "bias-free rankings" (which have no preseason bias at all) has BYU at #3.
Even if you look at FPI, BYU is #1 in Strength of Record, #10 in overall Efficiency, but #38(!!) in overall FPI. The ONLY explanation for that could be the extent to which prior season performance is still backed into the predictive rankings.
In general, resume-based computer rankings nearly all have BYU solidly in the top-10 (and many in the top-5 or higher). Predictive rankings (which still have preseason bias and last year's results baked in to some extent) typically have BYU much lower.