Comparing ECU to Cincy and UL is ridiculous. Cincy and UL have very substantial followings both locally and nationally. They both have winning traditions in sports on a national level. ECU is popular in Eastern North Carolina and won a few football games over a few years, many years ago.
I agree that ECU has not had much success in basketball and they were a bad basketball add to the AAC. I have friends who went to ECU and they are a football school with relatively strong football traditions. From 2007 to 2016, ECU football average about 44k to 45k per game which is pretty good considering who they were playing. From a football standpoint, they are probably the third most supported team in North Carolina.
Here some football attendance numbers relative to Louisville and Cincy:
2008: ECU 42k, Louisville 40k, Cincy 32k
2009: ECU 42k, Louisville 33k, Cincy 40k
2010: ECU 50k, Louisville 51k, Cincy. 35k
2011: ECU 50k, Louisville. 49k, Cincy 32k
2012: ECU. 47k, Louisville. 50k, Cincy. 29k
I had no problem adding ECU to the AAC FOR football as they had one of the biggest fanbases that made sense to add to the AAC, but their basketball team was a significant drag on the AAC.
From a TV contract standpoint, I would say that both Cincy and Louisville have more name recognition than ECU.