I live in Birmingham, and my real question is how many of the attendees bought their tickets from the UAB athletic department, at face?
Lots of companies around town buy tickets, often at a discount, and distribute them to employees as a perk, at no charge. A lot of times, the HR departments can't even give them away.
Admittedly, Legion Field is an abomination. UAB should build a 20-30,000 seat stadium on campus. The stadium should be designed with expansion in mind. If attendance justifies, they can always add on. If not (as I expect will be the case), they haven't flushed a ton of money.
But this is Birmingham, and common sense isn't very common.