The basketball world's biggest curiosity will be at the Wells Fargo Center in Philadelphia on Sunday.

The Big3 league, co-founded by rapper/actor Ice Cube, pits former pros against each other in a 3-on-3, half court format. There are eight Big3 teams that tour together like the barnstormers of old. Philadelphia is the league's fourth stop, following games in Brooklyn, Charlotte, and Tulsa.

The league is betting fans will turn out to glimpse former NBA stars such as Kenyon Martin, Chauncey Billups, Jermaine O'Neal, and Allen Iverson play a pared-down game that, hopefully, masks their declining athleticism. And there is star-power on the bench, too. Big3 coaches include Sixers legend Julius "Dr. J" Erving, Rick Barry, Gary Payton, George Gervin, and Clyde "The Glide" Drexler.

If those names aren't familiar, Big3 probably isn't angling for your business.

The NBA has long been a star-driven league centered around big personalities. The question is whether fans will still pay to see those stars after their athletic luster has faded.

"A big advantage is they're playing in the off-season," said Joel Maxcy, professor at Drexel University and president of the International Association of Sports Economist. "They're not going head to head with the NBA."

The Big3 isn't trying to replace or even really challenge the NBA. Three-on-Three basketball has developed its own following, so much so it will be an Olympic event in 2020.

The last half century, however, is a graveyard of failed or subsumed sports leagues, Maxcy noted. The USFL (football), the XFL (football-like product), and the WPS (women's soccer) all folded. Other leagues such as the AFL (arena football) and MLL (lacrosse) remain niche attractions.

There is at least some precedent for people watching former sports stars in their later years. The PGA's Champions Tour, formerly known as the Senior Tour, has lasted almost forty years. Crowds have flocked to see aging greats such as Tom Watson and Hale Irwin challenge each other.

Basketball, though, requires a very different form of athleticism.

"When you see a player whom you used to remember being able to rise well above the rim and is no longer able to do that...it is much more evident in a sport like basketball than it is in golf," said Michael Leeds, who chairs Temple University's economics department and specializes in sports.

It takes a discerning eye to spot the differences in, say, a 30-year-old golfer's game and 60-year-old golfer's game, said Leeds. Almost anyone can tell when a basketball player no longer skies for slam dunks or zips past defenders.

Asking people to watch diminished athletes play basketball "is really asking a lot of the fans," said Leeds.

He also worries Big3 has abandoned the "cardinal rule" of modern sports leagues by not pairing each team with a city. He wonders how the league will be able to drum up consistent interest without the geographic tribalism that drives so much sports fandom.

At least at the get go, Big3 will rely on big names and funky rules. Teams, for instance, can get four points if they shoot from one of three demarcated circles well beyond the standard three-point line. Instead of shooting two free throws for one point each after a foul, players shoot one free throw worth two points. The first team to score 50 points wins. You can read a full accounting of the rules here.

So far the Big3 has held games in Brooklyn, Charlotte, and Tulsa. While the games have been spirited, they're certainly not as high-flying as NBA action. The contests are a bid of a throwback in that they rely more on dribbling, passing, and shooting prowess.

Big3 officials hope the buzz and novelty will draw fans from far and wide whenever the show comes closest to their hometowns. Marcus Gwynn, 24, is one of those fans. Gwynn lives in Howard County, Maryland — between D.C. and Baltimore. He's planning weekend road trip to Philly.

"I'm trying to get the full experience — get a cheesesteak, maybe hit a bar or two," Gwynn said.

Gwynn wants another chance to see his favorite player, Allen Iverson. He's been impressed with the games he's seen so far on television. Sure, it's not NBA quality. But the players seem to care. And the 3-on-3 format feels relatable to him, like something out of his own childhood.

"Everybody plays 3-on-3," he said. "I'm terrible, but I'll go to the court just to play basketball with my friends because I'm competitive."

Plus, there's not much else to scratch his sports itch this time of year.

"Basketball season is completely done. I'm sitting here fiending for football. I'm a huge football fan, but I have nothing to watch," he said.