I have witnessed how NU fans can and will get behind the team. The caveat is that the team has to be competitive and actually win some games. When I was an undergrad in the early 80s, we made the NIT my junior year with a team led by seniors Jim Stack, Gaddis Rathel, and Michael Jenkins - all Chicago area boys. We also had local boys like Art Aaron and Paul Schultz. Ironically, this was during the first remodel of Welsh Ryan and we played that season at Alumni Hall in DePaul. That didn't stop the students from attending either.
As
@TheC experienced, the high school state tournament supersectional was played at McGaw Hall / Welsh Ryan, and I also experienced a full house there. It was electric, dirt floors and all.
A packed Welsh Ryan is one of the loudest venues, too.
Put a winning team out there, and the fans will come.