Every now and again someone gets it in their head that they want to do a sport-based RPG. It's a logical instinct - there's lots of great, classic sports stories out there, and they hit a lot of the same notes that make an RPG fun. I have nothing but admiration for anyone who wants to try, and I'm sure that someone will crack this nut someday, but in the meantime I want to call out the one big obstacle in the road that has been the doom of many of us, something I call the sports paradox.
The RPG Sports Paradox: The only way to make an RPG about a sport is to make an RPG that's not about that sport.
What does this mean? To understand it, take a minute to imagine a sports RPG. It doesn't matter much what the sport is, but the expectation would be that you would need rules for playing that sport. Seems obvious, but that's the trick - sports stories are not really about playing any particular game, they're about a destination. There are a couple of possible types of destinations, but they're mostly some variant of needing to win "The Big Game". The exact form of the Big Game is less important than the fact that it provides meaning to all the games along the way - they're the road to the destination.
And that's where the problem arises. Such a game will fall apart if the players lose a game. Oh, sure, there are some tricks you can pull to smooth over things ("The Maplewood team got food poisoning! We're in the finals!") but they have the clear stink of Deus Ex Machina about them. So you're left with two choices: You can either allow the players to lose their games (and hope they won't) or you can guarantee that they won't.
Allowing them to lose may be a viable option for a GM _running_ a game, but it's a bad decision for a designer unless you're very comfortable putting a warning label on your game that it could really end up sucking. It's an easy solution, and it produces unsatisfying games.
The alternative, guaranteeing victory, can be approached in a huge number of different ways, but they all have something in common - they shift to making play (and the challenges and fun in play) about things other than the game, like achieving personal goals, overcoming personal challenges, building the team dynamic and so on. These are good things, and they're the actual bread and butter of sport stories, and that's awesome.
You've just made play about something other than the sport. Play is no longer about the game on the field, as would be envisioned when you describe "A sports RPG".
So, that's the paradox and the trap. It doesn't just apply to sports, but rather to anything with a sports-like structure (Battle of the bands, Mortal Kombat, Shootouts at High Noon, Poker and so on) . If the narrative depends on a progression of wins to reach climax, then you're looking down the barrel of the paradox. And may god have mercy on your soul.
Now, I'll toss in my two bits here for anyone looking to crack this particular nut. It's not my white whale, but I'm sure it's someone.
The underlying system problem with this model is that it's fault intolerant. The fragility of the system is such that a single failure breaks it, so the trick to getting it to work may revolve around figuring out ways allow for failure in your particular narrative without being cheesy. There are a few possible models for it, some better than others. A hidden points system can kind of work, but the hand of the GM is pretty obvious in play. Similarly, you can put the players in a context like, say, college football, where the decisions on the final bowls have no relationship to previous play.
One system that I haven't seen done, but which might actually be fun, is to treat it as generational play, with each "Generation" being a season. If the players lose in a given season, you advance the clock and pick up at the next season. Obviously, this only works for certain structures - it might suit a game about high school soccer, but not one of underground martial arts battles to the death.
Whatever structure you settle upon, don't be lazy. The ultimate goal is not to be able to make a game that makes playing the sport matter without worrying about all that narrative crap. You want a solution that let's you bring those two elements together, so the dramatic and personal elements provide fuel for why your time on the field matters.
1 - One trick is to give the characters access to currency (plot points or the like) that can give bonuses in play, and allow an unlimited amount of them (effectively guaranteeing play) but then use the number or type of points used to fuel between-game problems. At first glance this seems like a great solution because the sport-play is still "real" but that veneer is very thin indeed, and doesn't hold up under heavy use.
2 - This is, BTW, the subtle distinction from a dungeon crawl. A single failure _could_ be a game ender, but the dungeon is more fault tolerant. There are many potential failure outcomes, including things like running away, getting captured or otherwise allowing the game to continue through a failure.