About the same time, UAB was leaving a dying Sun Belt, one that ironically was saved by a merger with the American South Conference, which included former member New Orleans. The Sun Belt also lost UNCC, VCU, ODU, and USF in 1991; all but ODU went to the Metro.

DePaul was independent, so obviously joining a conference, especially one with good basketball programs was right up their alley.

I'm not sure what prompted Marquette and Saint Louis to leave the MCC (now the Horizon League), as the MCC only had nine schools during their tenure.

Cincinnati and Memphis leaving the Metro for the Great Midwest looks puzzling in hindsight, as it did nothing for their football programs, which remained independent. I guess as in the case of Saint Louis and Marquette, it improved their ability to access the NCAA tournament, but that probably could have been accomplished by the Metro re-adding Saint Louis, and adding Marquette.

Had the mass exodus not occurred out of the Sun Belt, this might have been the Metro in 1991:

Louisville
Virginia Tech
Tulane
Southern Miss
Cincinnati (never joined Great Midwest)
Memphis (never joined Great Midwest)
DePaul
Marquette
Saint Louis

Houston would have likely still joined the Metro in 1996 after the Southwest Conference disbanded, giving the Metro seven members for football. Eventually East Carolina (initially football only), South Florida, TCU, UAB, and Army (football only) get added. Virginia Tech still leaves for the Big East.

If the American South could have survived to 2000, it likely takes in the remnants of Big West football, until the WAC adds Idaho, New Mexico State, and Utah State in 2005. That move likely forces the Sun Belt/American South merger that happened in 1991. The Sun Belt would have likely lost Charlotte in 2005 to the Atlantic 10 along with Saint Louis of the Metro.