LeBron James is talented enough and fortunate enough to have escaped the vagaries of sports for most of his career. In a league of perpetual chaos, he’s the closest thing to certainty. For the past 10 years, as long as he made the playoffs, he also made the NBA Finals. 

Until now. LeBron James lost in the first round of the playoffs for the first time in his career on Thursday, when the Phoenix Suns beat the Los Angeles Lakers, 113-100, in Game 6 of their playoff series to end their championship reign abruptly. 

The season turned out to be a wasted one for a star who doesn’t have many of them left. James is now 36 years old with 18 years of NBA experience. He’s been in the league for half of his life, and soon there will be players who weren’t born when he was a rookie. He was long ago pushing the limits of longevity. What he’s doing at this age is without precedent: He is still the game’s most dominant force.

But he is also nearing his twilight and chasing the shadow of Michael Jordan’s six titles, even if James long ago surpassed him in many statistical comparisons. For someone with a keen awareness of legacy, narratives and how championships spin both, James understands the importance of seizing every good opportunity that he gets. 

He did last season when he won his fourth ring. He had another chance this season. Instead the Lakers are out after the first round for the same reason they were stuck with this frisky Suns team: injuries. 

It’s hard to know what to extrapolate about his basketball mortality and how to interpret what might have been the most curious few months of James’s years in the NBA. After they bolstered their roster and rushed back from a short offseason after their lengthy stay in last season’s bubble, James looked like the league’s MVP and the Lakers were flying at cruising altitude near the top of the Western Conference. And then came turbulence. Anthony Davis’s calf and Achilles tendon sidelined him for 30 games, James missed 26 games with a sprained ankle (his lengthiest absence in a career that has been remarkably free of major injuries) and the Lakers had to beat Stephen Curry and the Golden State Warriors to land a playoff spot. 

They appeared to be recovering and rounding into form when they took a 2-1 series lead and a halftime lead in Game 4 against the Suns, who had emerged as one of the league’s bright spots in an otherwise gloomy season. But another injury blunted their momentum again. Davis strained his groin, the Suns stormed back and the Lakers suddenly found themselves in a surprising amount of trouble. 

They were smoked in Game 5 and cooked in Game 6, and it was once again traceable to injuries. Davis missed the Suns’ blowout in Game 5 and barely made it to Game 6. Less than halfway into the first quarter, fighting so much pain that walking appeared to be a chore, he limped into the locker room and watched the Lakers hobble into the summer. 

That was the story of their season. They couldn’t get healthy. They kept getting hurt. They got eliminated. “The injuries that we faced were just too much,” Lakers coach Frank Vogel said. 

The rest of the league will feel their absence. The dethroning of the Lakers ensures the first NBA Finals in a decade that won’t feature LeBron James or Stephen Curry, and it means the league’s biggest games will be played without the sport’s biggest television draws.

It also paves a road to the Finals for another team in the West. The Utah Jazz had the league’s best record, even if nobody outside Utah seems to realize it. The Denver Nuggets have the league’s MVP in the wondrous Nikola Jokic. The Los Angeles Clippers could be the favorite by next week if they’re not ousted by the breathtaking Luka Doncic and his Dallas Mavericks first. 

From left to right, Anthony Davis, LeBron James and Lakers coach Frank Vogel during a Game 6 loss to the Suns.

From left to right, Anthony Davis, LeBron James and Lakers coach Frank Vogel during a Game 6 loss to the Suns.

Photo: kirby lee/Reuters

But no team had a better first round than the Suns. After their 8-0 finish in last season’s NBA bubble, Phoenix traded for another 36-year-old legend, the wily point guard Chris Paul, in the hopes that he would sprinkle his pixie dust of basketball sorcery on a promising young roster. He delivered. The Suns went from a team that missed the playoffs last year—and every year since 2010—to a team that finished second in the West. 

Their reward for a fabulous regular season was the most fearsome No. 7 seed in NBA history. 

“I don’t look at our seeding,” James said before the playoffs. “It doesn’t matter.” 

As it turned out, it mattered very much. They might have been able to afford an injury against some other team. But the Lakers had a slim margin of error in this matchup, and it shrank when the Suns began playing like the No. 2 seed. 

Devin Booker capping his breakout performance by scoring 47 points in a sensational closeout game on Thursday made him a living, fire-breathing reminder of a deficiency that haunts the Lakers: They struggle with the part of basketball that requires putting a ball through a basket. 

The odd thing about this team is that at a time when NBA offenses have never been better—this season produced the seven most efficient offenses of all time—the Lakers were title contenders because of the NBA’s best defenses. When they won the championship last season, they ranked No. 3 in defensive efficiency. This season, even without James and Davis for months, they ranked No. 1. 

But in today’s NBA, if defense can still win championships, then offense can definitely lose them. The Lakers had the worst offense in the regular season of any playoff team. It got worse in the playoffs. Their offensive efficiency ranked 14th of 16 teams. The 16th? It belonged to the Miami Heat—the team the Lakers beat in last year’s Finals that was also bounced in the first round this year. 

What comes next is a question that tends to follow every season that doesn’t end with James swimming in champagne. 

The short-term answer is that instead of scouting the Brooklyn Nets, he will be selling his new “Space Jam” movie. The long-term answer is likely to be more of the same for the Lakers. They will almost certainly stretch their budget and tweak their supporting cast of role players, but James and Davis aren’t taking their talents anywhere. 

What they learned this season and last season is a lesson that will apply to next season and every one of James’s remaining seasons—no matter how many there might be. It’s that someone who has always forged partnerships with other brilliant players has never depended on a teammate so much.  

Write to Ben Cohen at ben.cohen@wsj.com