I don't know about having more upside than ECU, but Tulane and Tulsa are absolutely vacuums athletically. Tulsa tries, but they are tiny, and Tulane doesn't care. Casual UConn fans could care less about a mid-major league with a bunch of Southern schools that most of the fans couldn't find with a map if not for the fact that three of the schools in the league are named after cities.
The basketball conference sucks, which will degrade UConn's most valuable asset. Even one more Top 50/75 basketball program would make a huge difference to a league where half the teams will be outside the top 150 more often than not.
UMass is the flagship university of a major state, and academically it might as well be MIT compared to some of the schools in our league. That said, every decision we make with conference affiliation has been shortsighted, so keeping UMass out of the AAC is almost guaranteed.
I hate defending some of these schools, but Tulsa has a much better basketball history than UMass and they have greater fan support based on Tulsa having higher attendance than UMass virtually every year except during the Calipari years. (When Tulsa was good, they have been in the top 70 in attendance each year.) Tulsa has gone to 14 NCAA tournaments: 55, 82, 84, 85, 86, 87, 94, 95, 96, 97, 99, 00, 02, 03 and they have a record of 12-14. They won the NIT in both 1981 and 2001. UMass has gone to 8 NCAA tournaments.
As for Tulsa football, they have an impressive record and blows away UMass. They are ranked 43rd in FBS wins and 50th in winning %. They have gone bowling in 03, 05, 06, 07, 08, 10, 11, 12. And, although in the past, they have played in 2 Sugar Bowls and 1 Orange Bowls. In football, Tulsa will not be an easy win for UConn!