John McEnroe was sitting on a couch 43 stories above Manhattan, his gray curls and sleepy, crinkled eyes betraying every one of his 63 years, some of them hard ones, regaling an awe-struck podcaster with stories of his glory years. His rivalry with Bjorn Borg, his battles with chair umpires and his own demons.The awe-struck podcaster was Kevin Garnett, the N.B.A. champion, Olympic gold medalist and 15-time N.B.A. All-Star who is 17 years younger than McEnroe. Garnett was 8 years old when McEnroe won his last Grand Slam singles title in 1984.Somehow, that does not matter, not even a little bit.Thirty years after McEnroe played his last match at the U.S. Open, the irascible kid from Queens, the notorious hothead who griped and cussed and kicked his way across the hallowed grass of Wimbledon and every other tennis court, possesses a star power that has barely faded. It is especially bright during the U.S. Open. He is the leading voice of the tournament on ESPN, the subject of a new documentary, even the narrator and superego of a lovesick and unathletic teenage Indian American girl with a hot temper on Mindy Kaling’s comedy “Never Have I Ever.”The staying power is sweet revenge for the man whom much of tennis officialdom once viewed as toxic to their genteel game.“Maybe I wasn’t so bad after all,” McEnroe said during a recent interview at the end of a day that began with an early-morning appearance on “CBS Mornings” and then was jam-packed with chats with journalists, including from N.P.R.’s “Fresh Air.” “These guys who were trying to run me out of the game, maybe they should have been trying to help me instead of hanging me out to dry back in the ’80s.”‘The Weight of the Name’McEnroe won seven Grand Slam singles titles, plenty no doubt, but not as many as Jimmy Connors or Andre Agassi or Ivan Lendl, who each won eight, to say nothing of Borg’s 11, Pete Sampras’s 14 or Rafael Nadal and Novak Djokovic, who have tripled his tally.Yet, McEnroe still looms over his contemporaries, as well as Sampras, who dominated the era just after McEnroe’s. When he walks the grounds of the U.S.T.A. Billie Jean King National Tennis Center, he is still the quarterback of the varsity football team in the high school cafeteria.“Johnny Mac!” fans yell to him as he passes.If they can get a word with him, they often tell him how they liked how he thumbed his nose at authority, in a way that perhaps they have never felt empowered to.Word got back to Nadal last week that McEnroe was griping on television that the Spanish champion was violating the time limit between serves. “I’m going to have a chat with him,” Nadal said with a wry smile.He has written two memoirs and been the subject of multiple books. There was a feature film in 2017 about his rivalry with Borg, the Swedish great he vanquished into retirement. The next year came a documentary about him focusing on his brush with perfection in 1984. He has hosted a game show.John McEnroe and Coco Gauff during Tennis Plays for Peace, an exhibition to benefit Ukraine.Jamie Squire/Getty ImagesWhen the United States Tennis Association wanted to hold an exhibition to raise money for relief efforts in Ukraine, McEnroe was among its first calls. In that exhibition he played doubles with Nadal, Coco Gauff and Iga Swiatek. All are younger than his oldest child. He’d love a chance to coach Denis Shapovalov of Canada, the flashy and talented, but temperamental, lefty — sound familiar? — but has yet to get the call.Showtime released the latest documentary last week. The 100-minute film — McEnroe’s longtime agent, Gary Swain, is among the executive producers — is an exploration of his tortured psyche and the seemingly unfulfilled promise of someone who was, for a brief few years a long time ago, both the greatest player who ever lived and perhaps the most miserable.“The weight of the name ‘McEnroe,’ it’s heavy all across the globe,” said Barney Douglas, who directed the latest documentary.But why?McEnroe’s younger brother, Patrick, who also played professional tennis and now commentates (and squabbles) with him on ESPN, thinks he knows the main reason.“He’s authentic,” Patrick McEnroe said.Mellowing, Just a Little, With AgeDuring his playing days, John McEnroe may have been a bit too authentic. Tennis officials and some of their comrades in the news media viewed McEnroe as a menace to the sport. They fined and penalized him and threatened him with suspensions. They derided his penchants for hopping on concert stages to jam with rock stars and indulging in their late-night habits. The British press and the paparazzi hounded him so intensely, especially after his marriage to the actress Tatum O’Neal, that he skipped Wimbledon at the height of his career.As it turned out, McEnroe was already where tennis was headed long before it arrived, in good ways and bad.His game, which was all serve-and-volley all the time, may be completely out of step with nearly every top pro these days. But McEnroe possessed in spades something that continues to separate the best from the merely great — that magical and unteachable touch and creativity that allow a player to blast one shot and feather the next one. He could hit an opponent off the court on one point, then practically catch a 100-mile-per-hour forehand rocket on his racket on the next one.John McEnroe won the 1981 U.S. Open after defeating his rival Bjorn Borg in the final. He finished his career with seven Grand Slam singles titles.Photo by Professional Sport/Popperfoto via Getty ImagesHe also brought to the court the petulance and nastiness, the relentless attacks on chair umpires and equipment that have become so integral to the modern game, whether it was Serena Williams threatening to shove a ball down a linesman’s throat during her 2009 U.S. Open semifinal against Kim Clijsters or Nick Kyrgios’s tireless tirades at Wimbledon this year.The tennis gods blessed him with limitless talent. But they also saddled him with a mind prone to the anguish of tennis in a way that many top professionals now openly discuss. There have been therapists who have tried to help McEnroe explore that struggle, sometimes by his own choosing, sometimes at the direction of the legal system, with varying degrees of success, he said.And it all played out when television cameras first began treating tennis players like the reality television stars they are today. (Stay tuned for Netflix’s tennis version of “Drive to Survive,” the Formula 1 series, that is now in production.) That made McEnroe that rare character remembered, even lionized, not just for how he won but also for how he stumbled and fell short, a narrative of triumph and also a cautionary tale.“I was a little shy, and it was all a little overwhelming, and then somehow it all started to become magical,” McEnroe said of his journey.Like so many other modern stars of the game, though, he struggled to enjoy it.The tennis commentator Mary Carillo, a fellow New York native and his mixed doubles partner for their win at the French Open in 1977, recalled an 18-year-old McEnroe losing his temper with a waiter at a Paris cafe that spring. McEnroe spent several minutes yelling, “omelet du fromage,” which was the only French he spoke, at a waiter who ignored him. The waiter finally wandered over and quietly, but dismissively, told McEnroe, “The omelet is closed.”“To this day, when we’re arguing about something and I’m done with it, I just say, ‘The omelet is closed,’” Carillo said.John McEnroe argues with the chair umpire during Wimbledon in 1981.Bettmann / ContributorLooking back, McEnroe acknowledges a lot of what he sees in himself still angers him. Long before Djokovic and Kyrgios and plenty of others started using the coaches and family members in the player boxes to vent their frustrations, McEnroe directed an expletive at his father as he clapped for him during a match at Wimbledon.McEnroe later told him he was yelling at someone else in the crowd. His father accepted the explanation, though McEnroe is pretty sure his father knew he was lying.“It gave us both plausible deniability,” he said.Even his mother landed in the line of fire sometimes. He was still living at home when he won his first U.S. Open, sleeping in his childhood bedroom each night, eating his mother’s food, which he would impolitely order her to provide at a specific time before his matches.Fed up with his behavior, she asked him why he couldn’t behave more like his friend Peter Rennert, the tour pro who was his constant sidekick.“That made me feel like I was an inch tall,” McEnroe said.Age has mellowed him, though not entirely. His second marriage, 25 years and counting, to Patty Smyth, the lead singer of the rock band Scandal (“I am the warrior. …”), and six children have given him some perspective, as well as a few talking-tos when he gets out of line.But when he hears people saying his serve-and-volley game would not have a prayer against the likes of Djokovic, Nadal and Roger Federer, his voice rises to resemble that unmistakable ranting of the man who made chair umpires’ lives deeply unpleasant.Dial back time to the peak of his powers, put him on a grass court at maximum intensity, and McEnroe is comfortable in his belief that every so often he could have beaten the modern greats.“I would have gotten under the skin and made them think,” he said. “Would not have had a winning record, but I would have gotten to them a few times.”Sounds plausible. In his own way, McEnroe has gotten to all of us — and still does. More