That’s southern California. Fans have always been fickle, and games are attended by transplants who still support their home teams. Go to an Angels game when the Yankees or Red Sox are in town and you will be the minority. I went to a Ducks playoff game last year, or the year before, and everyone around me was from Canada. They were openly condescending, insinuating that SoCal fans knew nothing about hockey.
I was also a big Giants fan when Scramblin Fran played for them before going back to Vikings.