By Will Graves

RIO DE JANEIRO (AP) — Without it, Nadia Comaneci is just another gold-medal winning gymnast from Eastern Europe.

The Perfect 10 made the Romanian superstar more than a champion. It made her a legend.

Yet four decades after her barrier-shattering uneven bars routine in Montreal — the one that ended with Comaneci and coach Bela Karolyi initially staring at the scoreboard in confusion when it read 1.00 because it wasn't outfitted to put up the first 10.0 in Olympic history — perfection is harder to achieve.

The International Gymnastics Federation abandoned the 10-based system a decade ago in favor of a more complicated formula designed to better separate the best in the world. Yet something seemed to get lost even as gymnasts like American Simone Biles — heavily favored to win the all-around title on Thursday night — pushed the sport to unprecedented heights.

The scores Biles puts up are astounding. It's just that the 16s that Biles regularly posts on vault — a level her peers seldom match — don't translate. Yes, they're awesome. They're just not "perfect." And 28 years after the last 10 in Olympic gymnastics, Comaneci wonders if that needs to change.

"I think it would be nice to see something that everybody can understand," said Comaneci, who posted seven 10s in Montreal. "We are gymnastic family and we kind of know what's going on but everybody who loves gym and kids who are new to sport and they are fans, they don't quite understand the changes in the sport."

The new system divided scoring into two parts. One — the 'D' score — is based on what you do. The other — the 'E' score — is how well you do it. Gymnasts build their 'D' score throughout the routine by connecting one element to the other. The more connections, the higher the score. Yet the more you do, the more likely you are to get sideways at some point, dropping your execution score.

A little complicated, right? At the elite level, a good 'D' score starts at 5.0 and can reach 7.0. The 'E' score is set on a 10.0 format. Technically perfection is attainable. It's just that no routine has been awarded a 10.0 since the new system was introduced.

The closest the sport gets these days is Biles on vault, where her Amanar — a round off onto the block followed by 2½ twists — is unequaled. During U.S. Championships last spring, she landed it dead center of the mat with an almost imperceptible hop. The judges gave her a 16.3, including a 9.9 for execution.

What exactly was the problem? Well, U.S. national team coordinator Martha Karolyi has a theory.

"Guts," Karolyi said with a laugh. "Perfection is really very hard but I think on the other hand that the FIG a little bit intimidates the judges and educates them in a style that they are afraid to give higher scores."

Biles won't quite go that far. Asked if she remembers where she might have erred and she shrugged her shoulders and laughed.

"My toes might have been crossed maybe," she said, her tone making it sound more like a guess than a fact.

Longtime judge Kittia Carpenter was on the floor that afternoon in Indianapolis while serving as then coach for defending Olympic champion Gabby Douglas. She watched Biles soar. Was it worthy of a 10? Carpenter thinks it was as close as she's seen. Seeing it, however, and writing it down on a card is another matter.

"It is kind of in our minds as a judge that there must be something in there that I didn't quite catch," Carpenter said. "And you think that I couldn't possibly give a 10 or the whole world will come yell at the US."

Nellie Kim, a five-time gold medalist for the Soviet Union and the president of the FIG's women's artistic gymnastics technical committee, insists there is no mandate to keep judges from giving out a 10. She's also not about to apologize for making it near impossible. In the end, it's a subjective sport. At last fall's world championships, Kim likened gymnastics to a piece of art. What one person sees as beautiful, the other might not.

Gymnastics is not the only judged Olympic sport where the notion of "perfect" is rare. It's much the same in diving and figure skating, leaving the athletes to create an inner scoreboard of their own. They know when they've maxed out, even if the scores don't reflect it.

"I think you know it when it happens," American diver David Boudia said. "You know when you hit a dive because everything feels fluid."

The FIG created the new code to help continue to push gymnastics forward.

"You're always striving for something more," said four-time Olympic medalist Shawn Johnson. "Before, if you hit it (perfect marks), there was nowhere else to go. Now it is endless."

Maybe too endless. Germany's Fabian Hambuechen took the code to task after France's Samir Ait Said broke his left leg while vaulting during Olympic qualifying on Saturday for putting the focus on risk-taking rather than precision.

"It was like everyone had the chance to get the high score of 10.0 with different ways," said Hambuechen, a four-time Olympian. "Now everyone knows if you want to have a high D score you have to do these skills and these skills are sometimes too dangerous for some people."

There's another factor at play too: the 10 is relatable and marketable. A nice, firm round number, one that Comaneci made synonymous with greatness. They are still given out in the U.S. at the NCAA level and send a jolt through the arena and the athletes when they pop up.

"We took away the most iconic symbol of our sport," said UCLA women's coach Valorie Kondos Field. "It would be like taking away the Hail Mary when it's caught in the end zone. If you're a gymnastics fan and you see a 10, you talk about it the rest of your life."

Biles plans to put on a show Thursday night as she bids to become the fourth straight American to win the Olympic all-around title. She doesn't think too much about creating a historic moment by getting an ever-elusive score. Besides, even if she did, it might only generate more debate.

"Someone out there will say 'Simone's vault isn't perfect,'" Biles said. "If I'm happy with it, that's what I think matters the most."