UTEP compiled those envious attendance records while they were in the WAC and they were in the WAC before Boise became big. They weren't playing Rice, SMU, Tulsa, etc. or any other Texas schools. They drew well because their fans come out no matter who the opposition is. They did better in winning years of course but they did substantially better than 20,000 in losing years. Their fans came out to support their team. They did have one thing we don't have, traditional rivals in UNM and NMSU.
Boise cranked it up in the '90s playing Big West teams. They cranked it up with alum and community support, much as TCU has done. They had more donors in the '90s than we do now.
Saying we will do better in a better conference may not be a big selling point though it is clearly true. People complain about the conference we are in, well, we are in the conference we are in because we earned it.