Too many teams in the same area is the reason I was concerned when they admitted Marshall. I thought they were just adding another team to recruit the same players. However, Marshall still tends to recruit the Southern Conference area. The rest of the MAC doesn't get too many recruits from NC, SC, TN and VA. Marshall drew attention to the MAC and was one of the best moves they have ever made. And the MAC may have improved enough since Marshall joined that, ironically, they can benefit from losing Marshall.
The Marshall move to the MAC was almost one that didn't happen. Marshall applied for CUSA membership in 1995. At the time Marshall was a premier Division 1-AA program averaging 21,000 a game in a 27,000 seat stadium. Marshall lost out on CUSA by one vote, with Louisville voting against.
Once Marshall moved to the MAC, and won MAC championships in 4 of its first 4 seasons in Division 1A while bumping its attendance to 28,000 and expanding its stadium to 38,000, CUSA realized its mistake. In 2001, CUSA offered membership to Marshall. The only problem was this membership was football only, and the MAC only has all-sport members. Marshall tried its best to find another Division 1 league that would take their other sports but because of their location their wasn't any takers. So Marshall stayed in the MAC and Central Florida decided to join the MAC because they needed a conference and the MAC offered a low entrance fee while USF blocked them in CUSA.
If the ACC had not expanded turning the division 1A world on its ear, by 2005 UCF would more than likely be an all-sport member of the MAC. Little did anyone know what was to follow in 2003 when the ACC's overtures became public.