Based on the current CFP standings and assuming that the higher ranked teams are conference champs,

CFP
#1 Alabama (SEC)
#2 Oregon (PAc 12)
#3 Florida St. (ACC)
#4 Mississippi St. (at large)

NY6
Orange: #16 Georgia Tech (ACC) v. #6 Ohio St. (B1G/SEC/ND)
G5: #23 Boise St.
At Large (x5): Teams ranked #10 or higher

So, BYU would need to be ranked in the top-10 or higher to be a LOCK for the NY6 bowls.

Compare mythical undefeated BYU to #8 UCLA, #9 Georgia and #10 Michigan St.:

Mythical undefeated BYU
Overall: 11-0
v. Top-25: 1-0
v. 26-100: 6-0
v. 101+: 3-0
Good wins: at #23 Boise St., at 8-4 UCF, 8-4 USU,
Losses: none

#8 UCLA
Overall: 9-2
v. Top-25: 2-2
v. 26-100: 7-0
v. 101+: N/A
Good wins:#11 Arizona and #13 ASU
Losses: #2 Oregon, #25 Utah

#9 Georgia
Overall: 9-2
v. Top-25: 2-0
v. 26-100: 6-2
v. 101+: 1-0
Good wins: at #17 Missouri, #21 Clemson
Losses: 6-4 Florida, at 6-5 South Carolina

#10 Michigan St.
Overall: 9-2
v. Top-25: 0-2
v. 26-100: 6-0
v. 101+: 2-0
Good wins: 8-3 Nebraska, 7-4 Maryland
Losses: at #2 Oregon, #6 Ohio St.

Thoughts on where Mythical Undefeated BYU would rank?

For kicks:

#24 Marshall
Overall: 11-0
v. top-25: N/A
v. 26-100: 2-0
v. 101+: 9-0
Good wins: 7-4 Rice? 6-5 MTSU? (really?)
Losses: none