The BCS powers (Big Ten, Pac-12, SEC, the Universities of Texas, Oklahoma, North Carolina, plus Florida State and a couple more schools) have a great deal of say about the rules that govern the FBS ranks.
The last revision of rules made moving to the FBS ranks require an invitation from an existing FBS conference. This was a brilliant rule—it let market conditions in the bottom-tier conferences control expansion of the FBS ranks.
The six BCS AQ conferences would not even consider inviting any school directly from the far less prestigious Football Championship Subdivision (FCS) ranks (unless their arms were twisted due to a current membership, like Villanova's in the the Big East).
The middle class of the FBS ranks (the MWC and Conference USA) who were struggling to achieve BCS AQ status would likewise not want to invite schools from the FCS level—it would hurt the perception of them being deserving of a BCS AQ slot.
Only the bottom tier of FBS conferences (the WAC, the Sun Belt, and the Mid-American Conference) would feel comfortable inviting FCS programs or "I-AAA" schools who wanted to start playing football into the FBS ranks.
Those conferences feel they are not seen as peer members of the FBS, and as such they would feel real pressure to be selective and only invite schools that immediately generate additional revenue or exposure and/or enhance the esteem of the resulting membership.
Slots in these three conferences would be at a premium.
The MAC has more than 12 football members. (12 members historically has been a number considered to be one of a few optimal totals in scheduling terms for a conference—along with nine and 10). The Sunbelt is just shy of 12 members. The WAC has seven football members and a total of 11 all-sports members.
Football conferences have historically not favored expansion beyond 12 football-playing members, and the rules state that FBS conferences should have at least eight football-playing all-sports members (although the rules do offer a brief grace period for conferences that fall below the minimum.)
At the most, assuming all three conferences would be raided from time to time, it appeared that maybe seven or eight FCS schools would get invitations in the next decade or two, as the remaining 115 or so FCS schools endure the upcoming financial bloodletting Montana's former AD predicted last year.
The odds of another school like the University of Louisiana at Monroe (who lacked the enrollment to support FBS football or the local media market to to be a valuable asset to a conference) jumping to the FBS level looked to be greatly reduced.
The BCS schools would have a slow trickle of deserving candidates moving up to help keep the cost of body-bag games low. And the FBS bottom tier conferences would assume the role of the heavy in keeping the "riffraff" out of the FBS level.
The WAC could promote schools in the southwest, the Mountain time zone, and even California. The Sun Belt could promote in the southeast, and the MAC in the northeast.
It could be argued that every school in every region who wanted to play FBS ball had a path to the FBS—even if effectively there would only be seven or eight slots available in the next 20 years.
No FCS school that wants to play FBS ball is going to sue the Sunbelt or the WAC for not inviting them. It was a perfect solution.
MWC/C-USA merger threatens the FBS firewall
If the WAC gets pulled apart to the point where it eventually fails as an FBS conference, schools in the West (like Montana, Montana State, Portland State, UC Davis, Lamar, Cal Poly, North Dakota State, Utah Valley and others) may come to feel they have legal grounds to sue when they can't get invitations to the FBS ranks.
The Sun Belt, under the leadership of former WAC commissioner Karl Benson, could fill all their slots for the foreseeable future with WAC schools. Schools near the Sunbelt and MAC footprints will quickly exhaust those conferences' remaining hunger for expansion. The merged conference will have plenty of members soon and little appetite to refill from the MAC and Sunbelt ranks.
There may not be any slots for the deserving FCS upgrade candidates of tomorrow. With 24-plus in the Sun Belt and MAC and no WAC, who will take the Appalachian States, Georgia Southerns, Delawares and Old Dominions of the world when they are ready to move up?
Who will take the schools that have invested heavily into their programs to have the option of upgrading in the future?
The end of the WAC threatens to end the newly instituted quality control at the FBS level.
Today any school with the means and desire to play at the FBS level has a pathway to upgrade by just landing an individual FBS invite and leaving their FCS conference behind. The resulting FCS conference—minus one noisy FBS advocate—is far less motivated to move up.
That is a great process for the BCS powers, who want the FBS to grow enough to keep the FCS ranks subdued but want it to grow at a glacial pace, with much consideration to the merits of potential members beforehand.
When the FCS starts falling apart and there are no slots opening up for individual schools, FCS conferences (the CAA, MVC, Southland, and Big Sky come to mind) may start trying to sue or bring political pressure to allow them to move, as conferences, into the FBS to appease their most valuable members.
While BCS programs could obviously take an FBS Montana, are they going to be receptive to an FBS Northern Colorado or Idaho State? Do the BCS elite really want more Eastern Michigans in the FBS? Unwanted headaches could arise down the road.
It seems like there could be a compelling reason for the BCS AQ powers to prefer to see the WAC survive as an FBS conference.