I'm not going to be talking about Fantasy Football Leagues, or anything of the sort. Frankly, I don't know much of anything about those. Rather, I want to talk about the use of sports in fantasy fiction.
Now, I should preface this by saying, I'm not really a sports fan. At all. I went to Penn State and watched a grand total of half a game, and that was only because a sick friend wanted someone to take his season ticket so it wouldn't go to waste. I've lived with sports fans, my cousins and brother-in-law are big fans, and my agent is a huge hockey fan, so I'm aware of the mindset behind sports fandom. I don't share it, but I get it.
And, more importantly, I'm aware of how sports is important to societies as a whole. This is crucial in fantasy fiction. Unfortunately, it doesn't get quite the amount of coverage as it should.
Probably the biggest use of sports-- pure, game-for-the-sake-of-the-game sports-- would be Quidditch in Harry Potter. It's a flawed game, designed with a significant failure in sports logic-- the Seeker can instantly turn a 14 goal blowout into a victory-- but it as a cultural point for the wizarding world, it's great. Quidditch matches matter to the people playing them, and to the people watching them, even though nothing plot-wise is ever riding on them. Does it matter if Slytherin wins the Quidditch Cup? Not in the grand scheme of things, but it matters to Harry and his friends, so it matters enough. Though, if there is a flaw in the use of Quidditch, it's that it's the ONLY sport in the wizarding world.
I've only used it, so far, in Thorn of Dentonhill and other Maradaine books in a glancing way. The main game I've mentioned is tetchball, which is sort of a bastard child of rugby and cricket. I have a few others, but I haven't used them too much. Yet.
Are there other good examples? Most I can think of are more gladitorial fights rather than actual sports.