If you look at body of work through four games, here are the teams that have a legitimate reason to be ranked ahead of BYU. By the way, I'm not saying BYU is truly a much better team than their current ranking, but it's interesting to note how much preseason bias plays into it (or doesn't) four games in:

Top 25 teams with better resumes than BYU:
--#1 Texas (win at #10 Michigan)
--#5 Tennessee (destroyed #24 NCSt and beat #15 OU on the road)
--#10 Utah (win at #14 OkSt and vs Baylor, being on the road for their big win puts this into the top category)

Top 25 teams with similar resumes:
--#2 Georgia (Win over #14 Clemson and a close win over UK)
--#4 Alabama (win at Wisc who has two mediocre wins but still a good road win)
--#7 Miami (wins at FL and at USF, both mediocre but good road wins)
--#8 Oregon (wins against BSU and at Oregon St but close one at home to Idaho)
--#12 Michigan (win against #11 USC and loss to TX, loss to Texas shouldn't hurt them much but it is a loss)
--#13 USC (win against #13 LSU and a loss at Michigan, loss to Michigan shouldn't hurt them much but it is a loss)
--#19 Illinois (wins against #19 KU and at #22 Neb)

Top 25 teams with worse resumes:
--#3 Ohio State (three wins over nobodies)
--#6 Ole Miss (four wins over nobodies)
--#9 Penn St (Win at WVU but then two nobody wins)
--#11 Mizzou (win against #24 BC but BC probably inflated there since they got a bump beating FSU who sucks)
--#14 LSU (wins against SC and UCLA, but loss to USC)
--#15 Louisville (win vs Ga Tech and two nobodies)
--#16 Notre Dame (win at #20 TA&M but that loss at home to NIU is bad)
--#17 Clemson (two mediocre wins and a loss to UGA, UGA loss shouldn't hurt them much but it is a loss)
--#18 Iowa St (win at #21 Iowa and two other nobodies, Iowa might be a good win but who knows right now)
--#20 Ok St (win against Ark and a loss to Utah, loss to Utah shouldn't hurt them much but it is a loss)
--#21 Oklahoma (loss to #6 Tenn and three wins against nobodies, loss to Tenn shouldn't hurt them much but it is a loss)

Given all this I think the groupings are as follows:

Group 1 - better resumes and clearly ahead of BYU:
--Texas
--Tennessee
--Utah

Group 2 - similar resumes but eye test justifies them being in front:
--Georgia
--Alabama

Group 3 - worse resumes but eye test justifies them being in front:
--Ohio St
--Ole Miss

Group 4 - similar or worse resumes but eye test makes it arguable they could be ahead
--Penn St
--Miami
--Oregon
--Michigan
--USC
--Illinois
--Clemson
--Iowa St

Group 5 - worse resumes that should probably be ranked below BYU based purely on resume:
--Mizzou
--LSU
--Louisville

Group 6 - worse resumes that should definitely be ranked below BYU based purely on resume:
--Notre Dame
--Ok St
--Oklahoma

As such, without too much preseason bias I think BYU should be anywhere from #8 to #16 with anything up to #19 being somewhat reasonable. They're probably about three spots too low right now. I'm not saying BYU is the #8 team in the country! But based on resume alone I think an argument could be made. It looks like preseason bias is definitely in play for Notre Dame, Ok St, and Oklahoma and likely for Mizzou, LSU, and Louisville.