2011 - BYU muffs it when a Big12 offer is pending when the conference HAD OU and UT. BYU was forced into a position to go Indy, which nearly got aborted by Hair Thompson. Thus began 10 years of fruitless football nonsense.
2016 - The Big12, led by UT, parades four schools in front of the Big12 with the "intent" of deciding whether to invite anyone ... and doesn't, thereby strengthening UT and OU's positions of power.
2021 - OU/UT decide the SEC's grass is greener because 1) they'll get more $$$, 2) they'll have a better chance of getting into the CFP as an SEC also-ran than as a Big12 also-ran.
In all of this, think about where BYU would be today if BYU hadn't muffed it in 2011. Sure, BYUtv would be slightly less than the afterthought it is, but BYU would be sitting pretty as one of the most powerful "leftovers" in the Big12. Sorry, but 10 years in Indy exile has not done BYU any favors that being a member of the Big12 wouldn't have done better.
And, yes, joining a weakened Big12 is still better than staying Indy, if BYU is given the chance.