The Celtics’ Unexpected Success This Season

The 2025/26 season was supposed to be a “gap” year for the Boston Celtics. With 2:58 remaining in Game 4 of the Eastern Conference Semifinals last year, Celtics power forward Jayson Tatum tore his Achilles. Without him, the Celtics went on to lose the series and get eliminated from the playoffs. Coming into this season, The Athletic ranked the Celtics as the 26th-best team in the NBA, calling them a “sneaky candidate for one of the worst teams in the league.” At the time, no one projected the Celtics to perform as well as they did. Having just lost four key players to trades and free agency in the offseason and being without their number one option, they were rightfully underestimated. Their success despite these circumstances stemmed from great coaching and elite player development that allowed them to play at the level of a championship contender. 

Small forward Jaylen Brown was the driving force behind the Celtics’ success this season. Without Jayson Tatum, Brown became the primary offensive option for the Celtics. However, there were questions about whether he had the skill to replace Tatum. Brown quickly elevated his game, recording career highs in points, assists, and rebounds per game in a season. Additionally, he finished with the highest usage rate of his career, at 36.9 percent, meaning he was involved in more than a third of plays when he was on the floor. He finished as one of the best players in the NBA: The Athletic surveyed 159 NBA players on who was the best player in the league this season, and Brown tied for third place with 8.2 percent of the votes. Brown’s ability to step up from the second-best player on the Celtics to a top-five MVP candidate was essential to the Celtics’ unexpected success. 

The Celtics’ success wasn’t just driven by Brown stepping up but by role players rising at the right time. Despite losing four major players from last year’s team—center Kristaps Porziņģis, center Luke Kornet, center Al Horford, and point guard Jrue Holiday—the Celtics only made one major addition in the offseason: shooting guard Anfernee Simons, who went on to get traded for center Nikola Vučević at the trade deadline. Therefore, the Celtics were relying on players to develop into starters. Neemias Queta is a prime example of a player who stepped up into a starting role and succeeded. Last season, Queta was the fourth-string center on the Celtics, only starting six games. With the departure of the Celtics’ top three centers—Porzingis, Kornet, and Horford—Queta became the starter. Entering the season, there were doubts about Queta. An article on NBA.com predicted that the Celtics’ centers would “struggle matching up with the frontlines of the top six teams.” Queta finished the regular season 10th in defensive rating and as a candidate for the NBA All-Defensive second team. His improvements lifted the Celtics’ defense into a force to be reckoned with, playing a huge role in the Celtics’ growth without Tatum. Player improvement in the NBA is generally measured with the Most Improved Player award, which Queta is unlikely to win. However, many analysts argue on his behalf because he took the jump from an end-of-the-bench player to one of the top defenders on the Celtics. Celtics Coach Joe Mazzulla backed Queta for Most Improved Player, saying, “I hope he gets it, he deserves it.”

The environment created by Coach Joe Mazzulla made it possible for the Celtics to contend for a championship. He easily could have chalked this season up as a “gap” year and tanked for a good draft pick. But instead, he built a winning mentality in a locker room that ignored analysts’ expectations for the team. When Celtics point guard Payton Pritchard was asked if he was surprised by the results of this season, he said, “I’m not surprised at all.” Mazzulla’s success throughout his career and especially this season has hinged on his connection with his players. He constantly stands up for his players, which builds trust between him and them. Mazzulla also allows his players to have input on strategic decisions, including choosing their own starting lineup and defensive matchups. Celtics point guard Derrick White said on his podcast White Noise, “I think that’s the dope part about Joe—how much he trusts us. He wants us to think differently.” This is the reason Mazzulla is the current favorite to win NBA Coach of the Year. He took a team that was supposed to be in a gap year to the second seed in the east with his “player first” mentality. 

The last game of the regular season is a perfect representation of the Celtics’ player development and Joe Mazzulla’s coaching. Despite having already clinched second place in the Eastern Conference and having nothing to play for, the Celtics went into the game determined to win. They rested eight of their players, including all of their starters. Coming into the game, three of the Celtics’ five starters had started five or fewer games so far this season. However, the Orlando Magic, who they were playing, were still in contention for a playoff spot, so they were playing all their starters. Despite this, the Celtics won by five. Three Celtics players scored their career-high points in this game, with small forward Baylor Sheierman scoring 30, center Luka Garza scoring 27, and shooting guard Ron Harper Jr. scoring 27. This highlights the Celtics’ always-ready mentality, because players who usually only play in games that have already been decided were able to lead the team to victory by themselves. Joe Mazzulla isn’t concerned with who is on the floor or who his team is playing against; he’s solely focused on winning, no matter how little impact it has on their season.

Meanwhile, off the court, Tatum was working hard to make his return. Almost a year after his Achilles surgery, he made his season debut against the Dallas Mavericks. Predictably, he got off to a bad start, missing his first six shots, but he eventually settled in, scoring 15 points and grabbing 12 rebounds. In the 16 regular-season games he played, the Celtics went 13-3 and Tatum averaged 21.8 points and 10.0 rebounds per game, which is fewer points but more rebounds than last season, meaning Tatum’s injury did not cause a steep dropoff in his performance. Having Tatum back at almost full strength undoubtedly bolsters the Celtics’ chances of success this season, especially if he can return to his original level.

No matter what happens from here on out, this season is one to be proud of for the Celtics. The Celtics’ ability to succeed without Tatum for the majority of the season shows potential for a deep playoff run this year. But even if they don’t make a run, assuming they don’t suffer another major injury, they should have a great chance to contend for a championship next year and further into the future.