I forgot about the partial qullifiers and county sports schollies. I am still not convinced that B1G helped Nebraska in part because no real edge for out of state B1G talent and Nebraska seemed to get their out of state thugs from Cali. Tenn did not change conferences but schools around them got better. Twenty years ago I just don't remeber Ky, Louisville, Vanderbilt, Memphis, or NC (prior to Mack) being teams that were in the mix for talent. Even Ole Miss and Missouri for a while probably took a bite. Agree, Tenn is different from Nebraska because of the scandal, partial quallifier and geographic isolation are not present in Tenn. However the same lack of talent seems to be present, Nebraska because of the loss of in stae schollies and partial quallifiers and a change of conferences that took away Texas. I dont know if Calli was lost because of PQ or because B1G 10 states wont give up their in state players easily to Lincoln.
The first really big change - and I think the biggest change - was when the monopoly of the NCAA handling the TV contracts went away. There were so few games on TV back in the 70s and before, that only the blue bloods were on TV all the time - which included teams like Nebraska and Tennessee. So they could recruit nationally against teams that were lucky to get on TV once in a season. By the 90s and into the 2000's every single FBS team in the country could expect most of its games to be on TV, which leveled the field first for the non-blue blood P5 teams, and was disastrous for the blue bloods in talent-poor states. Nebraska and Tennessee still have advantages over lesser P5 programs due to history, booster involvement, passion, etc. but they are at significant disadvantage to teams closer to the talent. And a lot of that goes to the change in the TV landscape.
