I mean I know there's a pro Rugby league in England -- but I can't name a single team in it. Why? The sport just doesn't have the traction in its own country to where someone outside the country would ever see or hear from it. Actually, that's not true, I know Wigan is fairly decent in the sport. Though I have no idea how I know that. Crickett, I don't have the slightest clue about anything other than national teams. Where's the Derek Jeter or Lebron James of their 2nd and 3rd sports? I recall seeing a Rugby player on Top Gear once but that's the only time I've ever seen an interview with one of them.
Rugby is actually very big in the UK (though nowhere near football level, which is of course astronomical). The issue is that we in the UK don't have the US mentality of following a number of sports interchangeably. It's rare to find someone who actively follows both football and rugby. People who like football generally hate rugby and those who like rugby generally despise football. Cricket is similarly broadly popular, but because of its slow pace is treated like a casual sport, a quiet day out if you feel like it. Both sports have their LeBron James' and Derek Jeter's, (for the record, I've never heard of Derek Jeter before) but because neither of them are interested in marketing to foreign audiences, you've never heard of them. You really have to be in one of the cricket/rugby countries to know about them.
In Europe, people support teams that are relegated because they're still the biggest thing around even after they've gone down but if you're in America, why pay attention to a Boston soccer club in the second division when you have the Red Sox, Bruins, and Patriots all winning championships in the top division? Your hardcore soccer fan might but your casual sports fans would not.
That's actually kind of the opposite of the truth. In the UK, and indeed in most of the "football" (soccer) countries of the world, we have far less interest in regionalism. From a very young age you pick your football team - this is supposed to be your father's team, or failing that your local side, but inevitably a lot of pre-teenagers coming from families without a diehard fan in them just get seduced by success - and you are expected to stick by that choice for the rest of your life. Less-committed people do abandon their teams, or lose interest in them if they cease to be successful, but if you try to act as a diehard fan having previously switched teams, many of the hardcore support will simply refuse to acknowledge you, and will generally tell you to go back to supporting your original team. If you get mocked at school by fans of your rival team, and one day your team gets relegated and you tell them that you are going to support their team instead, you will get rejected by them, not welcomed.
The UK - indeed, Europe - is a small place, and even if you support a top-division team it's not unusual for your house to be closer to a better-supported, more successful team. Sticking by your team when they get relegated is nothing to do with the idea that your team is still the biggest thing around, because they inevitably aren't - there's always a bigger team than your own less than an hour's travel away from you.
For example, here is a map of London shaded by the areas of majority support for the different teams that play in London - and this is just for the professional football teams playing in the top four divisions of English football. There are many, many more non-league sides not shown here:
If we wanted to support a club based on following the most successful local side, you'd expect Chelsea, Arsenal and maybe Spurs to just walk away with all of the support in London, and most of south-east England. In fact, the dedication you're supposed to have for your club generally leads you to wish failure and disappointment on every other team in the region, because any other local club is automatically a major rival.
The difference is, football fandom here is tribal. Once you are committed to a team, you're there for life, and you're expected to simply accept the resulting highs and lows, because getting bored and switching to another team is a sign of a poor supporter. This, then, adds to the highly emotional charge which those fans who actually go to the games (in particular) feel for their club, meaning that winning promotion back to the second tier when you have been struggling in the third tier for a decade can provoke pitch invasions, and why, if you watch closely, on the recordings of Manchester City winning the title for the first time in 44 years, back two seasons ago, all around you you can see images of grown men in floods of tears without a hint of shame. Even now it's far from uncommon to see a thread on MCFC's forums saying things like "try to watch this without crying" or "just in case you wanted to sob again". The emotional commitment is just so great that you love your club like a member of your family, and you hate the other clubs in your region like they were your mother-in-law.
Well anyway, this really isn't furthering the debate. I just felt like answering that point. Sorry if I derailed the conversation a little.