I've never understood this thing about American sports where teams can just pack up and go to a new city and pretend to be the same team they were before... how can you be the same team if you're in a different city, and in some cases even with a new name? And yeah, obviously it would cost you most of your fanbase in your former hometown, especially when the city you move to has a natural rivalry with that former hometown.
It also doesn't make sense, considering the size of San Diego (in the top ten of largest US cities, as I recall?), to not have an NFL team in that city. I really didn't get that move.