Deontay Wilder, left, knocked out Artur Szpilka, on Saturday, in New York. Photograph by Frank Franklin II/AP

Boxing fans love nothing more than a knockout, and the same goes for boxers themselves, so long as they’re the ones doing the knocking. A year ago, when Deontay Wilder was preparing for the biggest fight of his career, he tried to get into character. He was an emerging boxing star—a heavyweight with a crushing right hand—and tradition obliged him to talk like a bullying brute. He promised to win by knockout, insisting that he and his opponent, Bermane Stiverne, were not merely competitors but enemies. “That will make a great fight, when two guys genuinely want to rip each other’s heads off,” he said. “I am in the hurt business, and I love being in it.”

Fighters are always talking this way, which doesn’t mean that we always believe them. Wilder comes from Tuscaloosa, Alabama, and he seems like a small-town guy revelling in his good fortune. He won a bronze medal at the 2008 Olympics, and he’s not too proud to brag about his third-place finish—he calls himself the Bronze Bomber. His rise has been marred by one ugly incident: in 2013, in Las Vegas, he was arrested after an altercation with a woman and charged with three counts of domestic battery; the charges were later dismissed. But in interviews, Wilder comes across as affable and unassuming, even when he’s trying not to. Last year, he beat Stiverne—not by knockout, but by an easy unanimous decision—and then celebrated back home, leading a parade through the not particularly crowded streets of downtown Tuscaloosa.

Wilder came to the Barclays Center, in Brooklyn, on Saturday night, for a fight designed primarily as a showcase for his knockout power. (No one besides Stiverne had ever fought Wilder and lasted until the final bell.) His opponent was Artur Szpilka, a Polish contender with an irresistible origin story: he is a former soccer hooligan, discovered by a perceptive coach who figured that a pair of boxing gloves wouldn’t unduly hamper his ability to brawl. Szpilka has since developed into a fairly skilled boxer, but he was still an underdog against Wilder. To make the long odds seem a little shorter, the boxers staged a series of confrontations. At a pre-fight media event inside the World Trade Center, the two men engaged in some conspicuously harmless pushing and shoving. Szpilka shouted, “You’re going down!” And Wilder cheerfully replied with the phrase he expected to hear the referee intone once the match was over: “And still!” As in, “And still the heavyweight champion of the world...”—even though Wilder’s so-called championship is merely one of many. (In fact, Saturday’s lineup included two purported heavyweight-championship fights, a bit of promotional overreach that elegantly exposed the absurdity of boxing’s bloated championship system.)

Like many knockout specialists, Wilder doesn’t look like a clobberer. He is six feet seven inches tall and lanky, and there is something adolescent about his fighting style, as if he only recently sprouted long limbs and he were still figuring out what to do with them. For eight rounds, he jousted, sometimes struggling to keep Szpilka at arm’s length, and sometimes throwing and missing wild punches—Wilder was winning, but not cleanly. Then, near the end of the ninth round, Szpilka, a southpaw, threw a wide left at Wilder, wide enough to give Wilder time to throw a straighter right in return, which arrived first, ending the fight. Szpilka whirled down onto the mat and landed on his back, with his hands above his head and his eyes closed. A perfect knockout.

But perhaps it is growing harder for fans and boxers to appreciate a knockout like that one without also appreciating its cost. Earlier this month, the New York Times columnist Dan Barry wrote an impassioned and disturbing account of a heavyweight fight that took place at the Theatre at Madison Square Garden in November, 2013: Magomed Abdusalamov, an undefeated prospect from Russia, lost by decision and started to feel head pain; medical officials didn’t take action, so he took a taxi to the hospital, where he was diagnosed with a brain clot and put into a coma. He spent almost a year in the hospital and is reportedly “paralyzed on his right side and unable to walk or to talk.”

The Abdusalamov tragedy (and, perhaps, the new attention inspired by Barry’s article) cast a shadow over Saturday’s fight. As Wilder celebrated, Szpilka was strapped onto a stretcher and carried out of the ring so he could be taken to a hospital. Although boxing tradition dictates that the lead post-fight interview goes to the victor, Jim Gray, reporting for Showtime, turned first to Szpilka’s trainer, Ronnie Shields, for a medical update. “He didn’t want to go to the hospital,” Shields said. “But as a precaution, the best thing is for him to go get checked out.”

Only then did Gray turn to Wilder: he had done exactly what he had been supposed to do, but now there was a faint suggestion that he had done something wrong. Gray, known for his prosecutorial (and often, therefore, effective) approach to interviewing, turned solicitous, as if he were trying to comfort the winner. “It’s part of the game,” Gray said, “But obviously, you don’t want to see a guy get damaged and hurt.”

“I don’t want to hurt the next man, so he can’t go back to his family,” Wilder replied—it’s harder, perhaps, to crow about loving “the hurt business” when you have just hurt somebody. He sounded almost penitent. “We risk our lives in here, each and every time, and as you can see, man, we don't know—he may be alright now, but in a couple days, you don't know what may happen. So he's definitely in my prayers, and I hope he's doing well.”

Other violent sports can afford to take a more flexible attitude toward violence. The N.F.L., which for years treated concussive blows as a marketing device, has lately grown more sensitive. Last week, when Vontaze Burfict knocked out Antonio Brown with a shoulder to the helmet, he was penalized fifteen yards and later suspended for three games. (Of course, the majority of violent football hits are treated less seriously. On Saturday evening, Danny Amendola laid out Jamell Fleming with a similarly brutal blind-side block; he was penalized but neither suspended nor fined, and after the game he was unapologetic. “We’re coached to do that,” he said.) Even mixed martial arts, the hybrid combat sport sometimes known as cage fighting, could conceivably take steps to protect its athletes from brain trauma. It is possible, though not easy, to imagine M.M.A. without head strikes—in a radically reformed version of the sport, fighters might concentrate, instead, on body blows, wrestling, and submission holds.

But boxing consists of little besides head strikes; a brain-rattling knockout is not merely one possible way to win but the ideal way to win. (Body-shot knockouts are thrilling but rare; judges’ decisions are anticlimactic at best and infuriating at worst.) Football referees can penalize “unnecessary roughness,” but in boxing, roughness is always necessary—roughness is the sport’s object, and the main source of its appeal. On Saturday night, Wilder confronted this truth for a few awkward moments before he was saved by a distraction that took the shape of an even bigger heavyweight: Tyson Fury, a six-foot-nine loose cannon from England who is widely considered the true champion of the division. Fury stormed the ring and grabbed the microphone, bellowing, “There is only one Tyson Fury!” He went nose-to-nose with Wilder, shouting, “I’ll beat you, ya bum!” To show that he was serious, Fury peeled off his jacket and loosened his tie, pacing the ring as if he were ready to fight right away.

Wilder got into the spirit. “You can run around like you’re a preacher,” he said. Fury is a Christian and sometimes talks about his faith in a way that seems designed to provoke. “But baby, I promise you, when you step in this ring, I will baptize you.” What did that even mean? No one could say. Maybe boxing fans will eventually get a chance to find out. (Though probably not soon: Fury’s next fight is supposed to be a rematch with Wladimir Klitschko, whom he beat last year.) If Fury vs. Wilder ever happens, just about every boxing fan will be hoping for the same thing. What we want is a knockout—at least, that’s what we think we want.