The Big Ten's problems are simple.
Their recruiting footprint is losing ground to the South and California and they don't get good enough players.
Just look at Nebraska's roster. It's got a ton of players from a state where the high school game is dying. Having another shark like Texas A&M kills them, nevermind schools like Missouri being able to sell the SEC.
If you aren't recruiting Cali/Texas/Florida and the deep South you are DOA in the national conversation.
It lost this ground decades ago, esp after most southern schools de-segregated.
I've been telling fellow BIG fans and critics alike, look at the Rose Bowl record & the transformation of de-segregation, especially starting in the 70s & definitely how the ACC, and most of all - how the SEC has adapted, along with Tex schools. The biggest beneficiary of all have been the Fl schools (UF, Miami, FSU) which make Fl by far the most successful state in terms of NCs since 1980 and it's the best state for recruits.
It's a simple formula: local prep talent empowers local & regional colleges.
The northern states have never had the proportion of rural-suburban environments of Black Americans like the south as well. This racial-ethnic group has always been far more urbanized in the north.
Btw, most northern powers have recruited nationally since the early 70s: Neb, ND, Mi, OSU, etc. ND has been the most successful, Neb next, but they had a solid Tx pipeline until joining the BIG.
The Pac12 and Ca is overstated. That state can't afford to feed the Pac12 in equivalent terms to states in the SEC, ACC and even Big12. Moreover, they have a home region advantage for the Rose Bowl, which matters more than given credit for.
The Pac12 has 3 AP titles since 1970, all USC & one is vacated. That's barely better than the BIG's 1.5 under actual conference membership. Bottom line, the BIG's best recruiting state, Ohio, is not on par with Ca in recruit production, mainly due to population, not per capita numbers.
My dad, a former sports writer, wrote in the early 80s that CF is a Sub Belt phenomenon especially - with far stronger post-season traditions than the northern states. Football, in general, is of course a national passion. But the NFL is so different than CF and the players mostly care about being on a team and getting a salary - A CAREER . Warm weather matters so much less at this point. I totally agree with my dad. And I've also been watching CF since the late 70s - the BIG had one great decade in my lifetime - the 90s.