Its called fairweather fandom. Look, the NFL runs in cycles and is designed for you to go 7-9, 8-8, or 9-7 most years. People around here still have that Vols, Alabama collegiate mindset that if it isn't 10-2 or better, its no good. And that ain't the NFL, or any professional league for that matter. The Patriots of this millennium are the exception to the rule........and there was no less desirable franchise before Tom Brady than New England. They dang near moved to Hartford.
The Titans were a dumpster fire between 2012 and 2015 and they lost a lot of goodwill during that time, but since then they've been competitive, albeit, leaving you wanting a little more. But short of a Super Bowl, I'm not sure what the locals want at this point.
Its not like they've saddled the city with decades of ineptitude like Detroit, Cleveland, Buffalo, or Cincinnati has. Truth is, Nashville has a lot of Atlanta's front runnerness to it. Hell, the Preds couldn't give tickets away until about 5 years ago. I hate that, because this is my home, but its true.