On Jan. 25, the Los Angeles Lakers went to Brooklyn to face the Nets and displayed a joyfulness that was unusual for them this season.

Their top stars LeBron James, Anthony Davis and Russell Westbrook were all healthy — one of only 21 times this season that happened. It was Davis’s first game back from a knee injury. It was James’s only appearance in New York City. He had been suspended for the team’s November visit to Madison Square Garden, his favorite place to play.

On back-to-back Nets possessions, James stole the ball and raced the other way as the crowd murmured in anticipation. They erupted into cheers each time James dunked.

After the second one, James grinned. He laughed with Michael Strahan, the former N.F.L. star, who was sitting courtside, and jogged back to the Lakers’ bench still smiling.

“The more minutes that we log, we continue to see how dynamic we can be,” James said after that game.

The Lakers were in eighth place in the Western Conference, and the night offered hope. At the time it felt inconceivable that a team built to be an unbeatable superteam might get stuck in the play-in tournament, but the Lakers had plenty of time to rise in the standings. Many assumed they could still be dangerous in any playoff situation.

Back then, few expected what would actually happen.

The Lakers were eliminated from playoff contention by the Phoenix Suns on Tuesday, even though James had the second-highest point average of his 19-year career this season. On Friday, James was ruled out for the final two games of the season because of a lingering ankle injury that had already kept him out of the three previous games. The Lakers are likely to finish 11th in the Western Conference, a spectacular failure for a team that expected to compete for a championship this season.

This season was challenging for many teams, as the N.B.A. attempted a return to normal with the coronavirus pandemic still happening and with high-profile injuries afflicting many teams. But no team in the league will finish the season with as large a chasm between expectations and reality as the Lakers did.

“It’s obviously disappointing on many levels,” Westbrook said. “But there ain’t much you can do about it at this point.”

Westbrook was introduced with superstar fanfare in August, as Rob Pelinka, the Lakers’ president of basketball operations, declared that he gave them a chance to win the franchise’s 18th championship. But his arrival didn’t come without questions.

How, for example, would a player who needs the ball in his hands to be productive fit with James, one of the best offensive facilitators ever? Was it wise for the Lakers to get older — by signing a slew of over-30 veterans — when they had already been plagued by health issues that often come with age?

Preseasons don’t always foretell the regular season, but the Lakers went winless in theirs.

When they stumbled at the start of the season, there was an easy way for the team to explain their situation: It happens. Superstars don’t always jell right away.

The pandemic offered an excuse — it made continuity nearly impossible for any team in the first few months of the season.

Pandemic disruptions reached their apex during the Omicron wave in November and December, during which dozens of players entered the league’s health and safety protocols.

The N.B.A.’s testing system wasn’t perfect and James suffered because of it — he flew home from Sacramento on a quarantine plane because of a false-positive coronavirus test result before a game against the Kings. It was the 12th game out of the Lakers’ first 23 that James had missed.

A few weeks later, a coronavirus outbreak spread through the team, even sidelining Lakers Coach Frank Vogel for six games.

Many teams, though, were hit even harder than the Lakers, including the Chicago Bulls, who had 10 players in health and safety protocols at once in December, and had to postpone two games.

Injuries offered another explanation for the Lakers’ stumbles. James and Davis missed more than 60 games combined — not an unexpected outcome, given their recent histories. Davis said he was “disappointed that we haven’t had a chance to have a full team.”

“Not sure how good we could have been,” he said. “With myself personally, two unfortunate injuries that kept me out for a while. That just came to be part of the season. As one of the leaders on the team, especially on the defensive end of the floor where guys need me to be out there, sucks for me, sucks for our team, our organization.”

But this season, injuries throttled many teams.

The Miami Heat lost Jimmy Butler for nearly a month. The Phoenix Suns lost Chris Paul for a month. The Los Angeles Clippers spent all season without Kawhi Leonard and lost their other star, Paul George, for three months.

While those teams found ways to adapt and keep themselves in the playoff conversation anyway, the Lakers couldn’t.

This was in part owing to a roster that was thinner than it should have been because of the resources dedicated to Westbrook.

To acquire Westbrook, the Lakers traded away young role players in Kentavious Caldwell-Pope and Kyle Kuzma. They declined to re-sign Alex Caruso, who went on to be an important defensive piece for the Bulls.

The Lakers’ defense was among the bottom third in the N.B.A. this season, as they have given up 112.8 points for every 100 possessions. The only team that has given up more fast-break points per game is Houston.

The Lakers also struggled to defend inside the paint, a symptom of their complicated big-man rotation.

During their championship season two years ago, the Lakers used JaVale McGee and Dwight Howard as their primary centers, occasionally asking Davis and James to fill the role. This season they brought back Howard, two years older and less effective. They signed DeAndre Jordan, 33, who proved past his prime as well.

They didn’t have the assets at the trade deadline to make a move that didn’t hamstring them further. Westbrook’s contract will become more attractive to other teams next year when he is on its last year, assuming he picks up his player option for the 2022-23 season.

As clear as it was that the Lakers’ roster was not working, it was even more clear that a fix would not come soon.

They were losing to the league’s bottom-dwelling teams. The best teams were beating up on them, too. Young playoff teams like the Grizzlies and Timberwolves were mocking them, with Westbrook’s poor shooting a regular target.

“This was the season that we just didn’t get it done,” Lakers forward Carmelo Anthony said. “We had the tools. Some things was out of our control. Some things we could control, some things we couldn’t. We didn’t get it done. We can’t make excuses about it. We just didn’t get it done.”

In the past nine years, the Lakers have missed the playoffs seven times. It is a previously unthinkable stretch for a franchise that was once used to competing for, if not always winning, championships.

This is a franchise that expects adding superstars will save them, and sometimes they do. This season that equation didn’t work.