There are moments — a whole lot of moments, really — in the new documentary about Barry Sanders where you can’t quite believe what you’re seeing is real, archival video and not a CGI creation. Sanders moves like an acrobat, pivots like a ballerina, hammers like a cannonball, all on the same play. Watching his unique combination of power and grace is as breathtaking now as it was back then — maybe more so, because those of us who watched it live didn’t quite realize at the time how rare and lucky we were to be living at the same time as Barry Sanders.

For all the mystery that surrounded Sanders — How could he move like that? Why was he so averse to individual glory? How could the gods be so cruel to put him in Detroit? — the overriding question, then and now, is: Why did Barry Sanders walk away from the NFL? Why leave when he was approaching the pinnacle, not just of his own career, but of NFL history?

“Bye Bye Barry,” a new documentary out this week from Prime Video, attempts to answer that question by asking it — once again — of the man of mystery himself. A production of NFL Films, “Bye Bye Barry” was made in conjunction with its subject. But unlike, say, “The Last Dance,” you don’t get the sense that Sanders is shaping a narrative to make himself look better … mainly because Sanders is, and always has been, just fine with whatever people think of him at any time.

“There’s a tradition in NFL Films of showing you who these players are behind the helmets,” says Ken Rodgers, executive producer of the documentary. “You learn their names from watching the games, but you learn who they are from our films. And Barry has the largest separation between public performance on the field and his very quiet, demure personality off the field.”

The documentary, which features everyone from Bill Belichick to Eminem, documents Sanders’ history from his earliest days on a football field. He was a remarkable high school running back in Wichita, Kan., who nonetheless drew only three scholarship offers: Iowa State, Tulsa and Oklahoma State. He hooked on with OSU and would go on to win the Heisman, but even in his earliest days there were clues about his values and his mindset.

Sanders once declined to go back into a high school blowout just to set a yardage record. He looked embarrassed when he won the Heisman in 1988 over Rodney Peete and Troy Aikman. And he didn’t throw a fit when drafted by Detroit a few months later, even though it effectively doomed him to a career of what-ifs and could-have-beens.

The Detroit segment of the documentary is pure, uncut nostalgia, from John Madden’s narration to old Nike commercials to the enormous shoulder pads worn throughout the 1990s. You’ll feel the exhilaration of watching Sanders break off run after magnificent run, and you’ll feel the frustration of Detroit utterly failing to match his skill, his effort and his potential with any complementary players.

Along the way, the puzzle pieces for why Sanders walked away begin to drop into place, from devastating injuries suffered by fellow players to the infuriating, championship-winning Cowboys — who surrounded their own apex-predator running back, Emmitt Smith, with a much higher caliber of talent.

Sanders walked away after his age-30 season. To put that in perspective, that would be like Derrick Henry retiring next year, or Patrick Mahomes in two years. He left the game less than 1,500 yards behind Walter Payton’s career rushing record. (Smith has since passed Payton, and Frank Gore has passed Sanders.)

“No one understands why he left the year he was about to become the best to ever play the position,” Rodgers says. “That's because we wouldn’t do that. We as Americans do want personal gain, even though we try to tell our kids it’s about teamwork and the love of the game.”

We often like to speculate on how social media would have affected certain athletes — how, say, Brett Favre or Deion Sanders or Joe Namath would have fared in an era where the world’s eyes are on stars around the clock. With some, you can guess. (Neon Deion in October 1992 would have been even bigger than Coach Prime in September 2023.)

With Barry Sanders, you already know. The man wouldn’t have embarrassed himself or his team with ill-advised selfies, he wouldn’t have shown up on someone’s TikTok video getting into a street fight in Vegas. He was thoroughly, defiantly true to himself … and for him, that meant keeping as low of a profile as he could while still being a superstar.

But what Sanders did just days before training camp opened for the 1999 season would have melted Twitter into slag. He was spotted boarding a flight to London, and then he faxed a statement to the Wichita Eagle — a statement which read, in part, that “my desire to be out of the game is greater than my desire to be in it.”

The documentary concludes with a brilliant bit of closure: Sanders returns to London, this time with his four sons accompanying him, to look back on what made him leave the NFL. His sons ask perceptive, knowing questions, but it’s clear that Sanders hasn’t even shared his innermost thoughts with them.

Lions fans get one more kick in the gut when Sanders speculates on whether Detroit’s perpetual futility played a role in his early departure. (It very much did.)

“If we were coming off a deep playoff run, a Super Bowl loss,” Sanders says in the documentary, “Those things do matter. And thinking back, I guess all I can say is, it could have made the difference, you know."

The Lions reached the NFC championship at the end of the 1991-92 season … which still marks the last time the franchise won a playoff game. Over Sanders’ 10 seasons, Detroit posted losing records in five of them and lost in the first round of the playoffs in four. The years of losing took their toll, both on his body and his psyche.

“That passion. It just wasn't there,” Sanders says. “There was nothing really left to play for.”

But Detroit has forgiven Sanders, and Sanders in turn has quietly embraced Detroit. He remains a visible figure in the city, and footage of the unveiling of his statue outside Ford Field shows the love that remains strong between city and star.

“I think he’s recognized not just as one of the greatest players in the NFL, but the very top of all athletes,” Rodgers says. “His status as an icon continues to grow. He’s going to be more of an elder statesman for the sport.”

Watch “Bye Bye Barry,” maybe on Wednesday evening while everyone’s dining on pizza, maybe on Thursday while the turkey’s in the oven. You’ll miss Sanders all over again. You’ll start to understand why he had to walk away when he did. And you’ll be thankful that you got the chance to see him at all, both then and now.