Vallejo is bar none the dodgiest town I have ever been to. And I used to live in Ballymun.
I haven't been there in many years. But it didn't strike me as being any different from any other mostly blue collar city.
I was there for 15 minutes waiting for a bus and weird stuff happened...
I would say therein lies the problem. If you want to get acquainted with the "weird" part of any town or city, just try using the public bus system. Or better yet, spend a couple of hours in the bus terminal. Americans use cars as their form of transportation for the most part.
What occurred in Vallejo with the base closure has happened in countless northern cities when unionized corporations fled to the South, and more recently with so many auto plant closings in Michigan. It is a terrible predicament to have only a handful of very large employers in a community.
OTOH Orlando is an example where nothing really happened when the US Navy closed down their huge training facility there. There were enough other diverse employers so that there was little or no economic upheaval.
The same thing occurred in Silicon Valley. It created a temporary spike of high tech job seekers. But the vast majority simply got jobs in the commercial sector, or they relocated to areas where there were still defense jobs.
The biggest problem in the case of many smaller or medium-sized cities like Vallejo is that many of the residents don't want to relocate. They have frequently spent their entire lives there and that often goes back many generations.
When the US finally gets around to dramatically downsizing the military, which will likely make the 90s downsizing loook miniscule by comparison, this is going to occur in a handful of other cities.