.. the data.
A few things to remember that drive ratings beyond your TV window:
1) "Are you a ranked team?"
2) "Are you playing other ranked teams or huge brands?"
3) "Are you in the hunt for the CFP?"
4) "Are you in the hunt for your CCG?"
The answer to those questions drive A LOT more general CFB fans (mostly from the mid-west & south), and fans of your big-brand opponents to watch your games.
(An additional factor here is did you play Colorado? Over 40% of TCU's viewers this year were from that one game vs CU. Likewise ~30% of Oregon's, 25% of USC's, and >50% of Stanford's total viewers came from their single game vs the Buffs).
Also, being ranked earlier in the season is helpful as it sets a team up for better TV windows through the year. Arizona is an example of a team that came on very late into the rankings, but was still dead last among all the Big12/PAC teams in total viewers. They've practically lived on the PAC12 network for the last few years...
If you look at the list (copied in below) you'll notice that all of the teams above BYU were ranked in the AP poll at some point in the season (TCU was only ranked in pre-season, but again, they'd be WAY below BYU if not for that 7M+ viewers vs CU). Also, quite a few teams below BYU were ranked at some point in the season. So BYU is somewhat of a viewership outlier by that slice.
Another way to gauge how much "who you played" helped your viewership is to see how many teams each program played above them on this list. BYU played 4 teams in the top 10 viewership on this list (only 1 in the top 5), while Utah played 5 teams in the top 7 from this list. Also, the top 3 non-OU/UT Big12 teams (TCU/Kansas/BYU) all played both OU/UT, helping to boost total viewership.
Honestly, it wasn't a gang-busters viewership year for either BYU or Utah. BYU never really "got out of the gates" and into the rankings, and Utah limped (literally) to the finish line despite being ranked nearly all year...
I still think thoughtful analysis of the data show BYU continues to have a VERY HIGH FLOOR for TV viewership, even when performing poorly, due to a strong core of devoted fans, thus "earning" the Cougs relatively good TV windows this past year, )especially when compared to the other 3 new Big12 additions from the AAC.)
It's pretty clear that no one in the new Big12 will be able to "ride the viewership coat-tails" of big draws like Texas/OU/USC/Oregon/Washington anymore. Should be interesting going forward, though BYU has the fanbase and brand to be in the top viewership tier when performing well, and even well above average when not.
Colorado 54.01M
Texas 43.26M
Oregon 33.81M
Washington 32.69M
USC 31.81M
Oklahoma 28.77M
Oregon St 20.86M
Utah 18.31M
TCU 17.06M
Kansas 14.85M
BYU 14.49M
Oklahoma St 13.68M
Iowa St 13.62M
West Virginia 13.13M
Washington St 12.95M
UCLA 12.39M
Kansas St 11.77M
Texas Tech 11.13M
Arizona St 7.24M
UCF 7.18M
Houston 6.96M
Stanford 6.59M
Cincinnati 5.77M
Baylor 5.45M
Cal 5.31M
Arizona 4.69M