For comparison here are the NCAA Tournament stats for Dayton, an BE expansion darling here at the Boneyard, and St. Louis, who is also often mentioned.
Dayton - 4 appearances and 2 wins (3 if you include a First Four round win)
St Louis - 1 appearance
Memphis is on par with those two, and imo has higher upside than either. You can disagree with it, but it’s not egregious.
For additional comparison, let’s look at some current BE teams:
Seton Hall: 5 appearances, 1 win
St. John’s: 3 appearances, 1 win
Georgetown: 2 apperences, 1 win
DePaul: …
Memphis would do at least as well as 1/3 of the membership and probably benefit from a recruiting bump from being part of the BE.