LAS VEGAS — The burst was gone. Just non-existent. Nathan MacKinnon tried — did he ever try — but he had nothing. No push, no jump, no chance. The man who had more speed bursts of over 20 mph than 99 percent of the league this season, the man whose explosive first step is among the best any of us have ever seen, the man whose game is built on speed — puck-handling with speed, shooting at speed, running over defenders with speed, wreaking utter havoc with speed — didn’t have any. Didn’t have anything.MacKinnon’s right leg seemed pretty much useless, the flesh and bone damaged by a Shea Theodore slap shot, and you can’t push off the left if you can’t land on the right, and you can’t push off the right with a knee that can barely bear any weight. And so MacKinnon, hockey god, was rendered mortal.For 1 minute, 59 seconds, and with Mitch Marner in the box and the Colorado Avalanche somehow trailing a game that had looked like it would be a laugher, MacKinnon gutted it out and tried to adapt in the third period of Game 3 against the Vegas Golden Knights. He coasted. He took cautious little strides. He barely crossed over as the Avalanche regrouped, steering more than skating, and watched helplessly as Martin Nečas took the drop passes and futilely tried to enter the zone — MacKinnon’s job, the job he does as well as anyone in the league.MacKinnon, perhaps the best hockey player on the planet in the prime of his career, looked more like late-stage Alex Ovechkin on that power play — lurking, lingering, hoping an open look or a one-timer would find him, because he didn’t have the structural integrity to find it himself.Did he ever try.“You might have to kill him to get him off the ice,” said his goaltender Scott Wedgewood.Might have to. But it might not matter now. MacKinnon’s will and fire and compete might not be killable, but that gutsy shot block that blew up his right knee now looks like the death knell of Colorado’s season, a season that began with such dominance and such promise.Just like Game 3 once did.The Avalanche team that lost just twice in regulation in its first 40 regular-season games has lost three straight to the Vegas Golden Knights to open the Western Conference final. Sunday’s shocking collapse — a 3-0 lead that became a 5-3 loss and a 3-0 series deficit — left the Avalanche struggling to comprehend what had just happened.“I mean, it’s not over yet,” captain Gabriel Landeskog protested. “First to four. Lick our wounds, come back to work tomorrow.”But only four teams in NHL history have pulled off a reverse sweep, and only one team has done it this late into the postseason — the 1942 Toronto Maple Leafs rattling off four straight against the Detroit Red Wings in the Stanley Cup Final. That’s 84 years — since the days of World War II — since someone has pulled off what Colorado now must attempt.“If any group can do it, it’s this group,” Wedgewood said.He’s right, of course. A Colorado sweep hardly seemed out of the realm of possibility when this series began. Vegas was a good team, a tested team, sure, but the Golden Knights were in danger of missing the playoffs entirely not that long ago. And the Avalanche were a machine, racing out to an absurd 31-2-7 start, cruising to the Presidents’ Trophy, sweeping the Los Angeles Kings and knocking out a Minnesota Wild team with legitimate championship aspirations in just five games.But now? The thought of these guys winning four straight seems as far-fetched as winning four straight spins of roulette. Vegas suddenly looks like the indomitable team, showing “some balls,” in the eloquent words of their last-minute replacement coach, John Tortorella. And Colorado looks utterly broken. Physically, yes — MacKinnon is clearly hurt, Cale Makar returned but seemed hesitant to take full-blown slap shots with what is believed to be a shoulder injury, and Valeri Nichushkin missed the entire third period — but also mentally. Players sat in stunned silence at their stalls in the locker room after the game. And the few who were asked to describe what had just happened couldn’t. A team full of joy and a confidence that bordered on well-earned arrogance was suddenly bereft.Even head coach Jared Bednar was at a loss. Asked how he expects his team to respond to such a gutting loss — of a game, of maybe a superstar — and all he could do was shrug.“We’re not there yet, I don’t know,” he said. “Everyone’s down in the dumps right now, and that’s what the next 36 hours are for, to get our team back and make sure our focus is in the right place. It seems like a tough hill to climb.”Fortunes in Vegas are won and lost in an instant, and the Avs were this cruel and ruthless city’s most recent victim. The whiplash of the first two periods was hard to process in real time, let alone explain after the fact.The Avalanche had the perfect first period. They scored first, then never let up. On the very first shift, MacKinnon went in hard on the forecheck and set up a Landeskog scoring chance, setting the tone for an utterly dominant 20 minutes. At the end of it, they had a 3-0 lead — Landeskog scoring after Devon Toews won a 50-50 puck and powered his way to the net in a virtuoso effort, with Nazem Kadri scoring off a slick Nečas feed after Josh Manson found Nečas with a terrific stretch pass, and Jack Drury scoring a short-handed goal just 41 seconds after the Avs caught a break when Pavel Dorofeyev’s power-play goal was waved off for barely nicking the outside of his glove.They looked fast and decisive with the puck. They were aggressive. They were physical. They won battles. They buried chances. And they even got a little luck. Everything they’ve been saying would happen since the series began. This is the NHL’s version of the Harlem Globetrotters, after all, capable of making any team look like the Washington Generals on any given night.The Western Conference final, finally, was on.And then it all fell apart.A returning Mark Stone scored a power-play goal for Vegas 19 seconds into the second period, and all that momentum vanished, and all the bad habits that plagued the Avalanche in the first two games of the series immediately reappeared. They looked a step slow and hesitant with the puck. They were timid. They were out-muscled. They lost battles. They started missing the net again. And the bounces started to go Vegas’ way, as Lady Luck always tends to favor the bolder side.Less than four minutes after Stone’s goal, Wedgewood punched out a big rebound that Parker Kelly took a weak swipe at, teeing up a William Karlsson goal. Eight minutes later, Wedgewood couldn’t fully stop a tipped Dylan Coghlan shot, allowing Keegan Kolesar to pick up the loose change in the crease to tie the game. Right after that, Brock Nelson missed the net high on a clear look. Moments later, Nelson found the crossbar on another breakaway sprung by Manson. It was Games 1 and 2 all over again.“Everything,” Bednar said when asked what fell apart. “Yeah, the first nine minutes (of the second) kind of looked like portions of Game 1 for me and parts of Game 2, where we mismanaged the puck on breakouts. Then they just got more competitive and we didn’t stay with that intensity for nine minutes. … For me, it’s those nine minutes, those two goals — pretty much an onslaught.”Thirty-one seconds before Kolesar’s equalizer, MacKinnon did what any hockey player would do in any game, let alone the conference final — he threw himself in front of a slap shot. MacKinnon slumped straight to the ice, in obvious pain. But before crumpling in a heap and laying prone for a full minute in absolute agony, he got up to one knee and cleared the puck out of the defensive zone.Because that’s what hockey players do.“Expect that from anybody,” Landeskog said. “Everybody.”MacKinnon wasn’t available to reporters after the game, likely getting treatment on a surely swollen knee. But there was no need to ask him the question. He would do it again, every time. And as devastating as the sight of him limping down the tunnel to the locker room after laboring his way through a 16-second shift was for the Avalanche, it was just as inspiring to see him come back out of that tunnel 2:24 into the third period, hopping up and down trying to get loose before stepping through the door for a shift.Landeskog is the captain and the emotional heartbeat of this Avalanche team. But MacKinnon is its leader on the ice, its best player, the source of its fire and drive.“Just kind of the person he is, and the competitor he is,” Wedgewood said. “Proves that every time he’s on the ice. He wants to win more than anybody, and (this was) just another example.”His third-period shifts should have been inspiring and invigorating. Instead, they were depressing. Imagine the devastation the Avalanche felt when seeing a drastically diminished MacKinnon shuffling down the ice, gutting his way through those four third-period shifts.Down a goal. Down 2-0 in the series. And now down to a fraction of a MacKinnon, a guy who’s missed just five games in the past three seasons. Seeing it all slip away — the game, the series, the season, another year of what looked like a wide-open championship window.“It’s low,” Bednar said of team morale. “As low as it can get, because it’s a big hill to climb. … You’ve got to find a way to get over it.”Yes, Scott Wedgewood, if any team can, it’s the Colorado Avalanche team that tore through the NHL all season, one of the most dominant clubs the league has ever seen.But this isn’t that team. Not anymore. Not with its confidence shot. Not with its superstar defenseman limited. Not with its superstar center — its heart, its soul, its fire, its physical embodiment of pure will — hobbled, a mere mortal.