After two seasons that were dramatically disrupted by the coronavirus pandemic, the N.B.A. thought it was returning to some version of normal this year. Instead, a wave of infections in the past few weeks has had a major impact on rosters and schedules, prompting game postponements and sidelining key players.

Before that, though, several key story lines had begun emerging on the court.

Golden State and Phoenix have established themselves as the best teams in the Western Conference, while the Lakers, laden with former All-Stars, have struggled to find their way. And even though injuries have stymied the Nuggets as a team, their big man Nikola Jokic has been making a case to win the Most Valuable Player Award again.

The Chicago Bulls have proved to be surprising contenders with a team of former castoffs who have played brilliantly together. In the East, only the Nets have a better record than the Bulls, despite playing without Kyrie Irving so far this season.

While Irving’s absence has to do with his vaccination status, two other stars have been out for contract-related reasons — Houston’s John Wall and Philadelphia’s Ben Simmons. How their situations resolve could have consequences for the way players and teams resolve conflict in the future.

With Christmas Day — what some consider the unofficial start of the N.B.A. season — looming, here’s a look at three important story lines so far this season.

Stars Go M.I.A.

By Scott Cacciola

Even before teams began cycling through replacement players to deal with Covid-related absences, some big names were missing this season.

There is, of course, the soap opera in Philadelphia, where Ben Simmons requested — demanded? — a trade from the 76ers over the summer. A standoff ensued before Simmons, a three-time All-Star and the team’s starting point guard, made a couple of cameos at preseason practice. The 76ers subsequently suspended him for conduct detrimental to the team. Daryl Morey, the 76ers’ general manager, has said that he will trade Simmons only for a “difference maker,” and he has clearly been methodical in his approach to weighing offers.

In Houston, the Rockets are undergoing a rebuild — and John Wall does not figure into their plans. Wall said in September that he and the Rockets agreed he would not play while the team sought a new team for him. But Wall is 31 with a surgically repaired Achilles’ tendon, and his onerous contract includes a player option worth more than $47 million next season. The search for a trade partner continues.

And in New Orleans, the Pelicans are still awaiting Zion Williamson’s return to the court — a theme that has become all too familiar to fans. After undergoing off-season surgery to repair a fracture in his right foot, Williamson has experienced a series of setbacks. His scheduled return to practice this month was scuttled when he reported soreness in his foot. Medical imaging later revealed a “regression” in the healing process, which led the team to abandon any sort of targeted timeline. He remains indefinitely sidelined.

When healthy, Williamson has been one of the league’s most dynamic young players. The No. 1 overall pick in the 2019 draft, he was named to his first All-Star team last season. But he appeared in just 24 games as a rookie because of a torn meniscus in his right knee, and has now played in just 85 career games while missing more than 90. Without Williamson, a bruising forward who is 6-foot-6 and not particularly slim, the Pelicans have scuffled to one of the worst records in the league.

Surprise Success: The Chicago Bulls

The Chicago Bulls’ resurgent season was interrupted last week when a coronavirus outbreak sent 10 of their players into the league’s health protocols and the N.B.A. postponed two of their games.

They returned to play Sunday, still depleted, in a game against the Lakers, and got right back to winning.

The Bulls have been led by DeMar DeRozan, whose emphasis on midrange jumpers has led him to be treated like a relic. DeRozan is averaging 26.8 points per game this season, ranking fifth in the league. He missed 10 days after entering the coronavirus protocols with what he told reporters in Chicago was an asymptomatic case.

While he was out, the Bulls relied more on guard Lonzo Ball, who has made dazzling assists all season and is running the team’s offense beautifully. Chicago recently lost a second-round pick after the N.B.A. concluded that the Bulls had tampered in order to sign Ball in free agency over the summer. But that penalty might have been worth it: Ball is shooting better than ever, especially from 3-point range, where he has made more than 40 percent of his shots.

Zach LaVine, who starts at guard alongside Ball, has had nearly identical statistical production to DeRozan, including averaging 26 points per game. Meanwhile, center Nikola Vucevic is averaging double-digit rebounds.

Off the bench, Alex Caruso has changed games with his defensive intensity, and is averaging two steals per game — second best in the league. Caruso’s defense is what earned him a shot in the N.B.A. to begin with.

The success so far is a welcome change for a franchise that hasn’t been to the playoffs since 2017. The Bulls last made the Eastern Conference finals in 2011, led by Derrick Rose and Joakim Noah.

They won’t play with the marquee teams on Christmas, because few saw this start coming. But they’ll have plenty of chances to prove they belong among the best in the league.

An Underrated M.V.P.?

By Sopan Deb

Nikola Jokic can’t jump particularly high or move all that fast. He’s rarely the most muscular player on the floor.

But Jokic is having the best season in the N.B.A. While players like Kevin Durant, Stephen Curry, Giannis Antetokounmpo and LeBron James are often cited as the top candidates to wear the best player crown in this era, Jokic is outproducing them all. He’s somehow playing even better than last season, when he won the Most Valuable Player Award.

For context, explore his advanced numbers: Entering this week, Jokic was at .312 win shares per 48 minutes, a measure of how many wins can be attributed to a player. His was the best in the league, and on a pace to be the 10th best in N.B.A. history. Another number: Jokic’s player efficiency rating, a measure of contributions per minute, was 34.22 entering this week, the highest in the league. He is even been better on defense.

When we watch Jokic play basketball, we aren’t just seeing one of the N.B.A.’s best in his prime. We’re watching one of the best players of the last 30 years. But he hasn’t been a part of much M.V.P. chatter this season. After Denver’s run to the Western Conference semifinals last season, the Nuggets have been mired around .500 for most of this season, in large part because two of their top players, Jamal Murray and Michael Porter Jr., have been injured.

It’s too bad, because when Jokic is on the floor, the Nuggets are among the best teams in the N.B.A. statistically. When he’s not, they’re among the worst on both ends of the floor. It’s difficult to be more valuable than that.