Has this ever happened before?

Colorado State Coach Larry Eustachy may just employ a starting lineup this season consisting of all transfers:

"...In fact, Eustachy's entire starting lineup could likely be comprised of transfers — as guards Antwan Scott (Grambling State) and Daniel Bejarano (Arizona) and forwards J.J. Avila (Navy), Stanton Kidd (North Carolina Central) and Tiel Daniels (Southern Illinois) all began their college careers elsewhere. Guards Gian Clavell (Northwest Tech), John Gillon (Arkansas-Little Rock), Fred Richardson III (Lee College/Oregon) and forward/center Marcus Holt (Paris Junior College) are also with (at least) their second school..."

So there's no competition in calling CSU Transfer U.