Back in July, Derrick White got a call from Joe Mazzulla.
“He calls me, and he’s like, ‘Happy birthday, man.’ And I’m like, ‘Appreciate it.’ And he’s like, ‘Everybody thinks we’re gonna suck, I love it,’ and he hangs up,” White said. “He’s like, ‘I can’t wait for us to get back out here. I think we could be so good.’”
As the book closes on the Celtics’ 2025-26 regular season, Mazzulla’s message aged pretty well. They weren’t just good, they were one of the best teams in basketball.
After trading away Jrue Holiday and Kristaps Porzingis, losing Al Horford and Luke Kornet in free agency, and with Jayson Tatum sidelined by a ruptured Achilles with no clear timetable, expectations cratered. Their preseason 41.5 win total reflected it, sitting as their lowest total in over a decade (2014-15 season).
The talk of tanking was loud. It only got louder after a 0-3 start.
But even then, inside the locker room, belief never wavered.
“When we lost our third game of the year to Detroit, me and Joe [Mazzulla] were walking off the court, and we said to each other, ‘This is only going to make us stronger,’ and that we were going in the right direction now,” recalled Payton Pritchard. “A lot of people didn’t think that losing our third game, but I remember like, ‘Ok, we’re gonna start turning the corner.’ And then little by little, every day getting a little bit better and started getting there.”
That 0-3 stretch ended up being their longest skid of the season.
From there, Boston went 56-24, finished 56-27, and claimed the No. 2 seed in the Eastern Conference by January, and never let it go.
“Obviously, we’ve got one more left, but that’s something to be proud of,” Sam Hauser said of the Celtics’ campaign. “And being the two seed in the East is something to be proud of. Coming into the year, we had faith in ourselves, I think, but we didn’t really know how it was going to look, and you kind of could tell within the first 10 games that we were trying to figure it out. But sometimes the best way to figure yourself out is trial and error. And throughout the year, I think we just got better and better and better and really bought into the identity of just being the harder-playing team.”
That harder-playing identity showed up all season.
The Celtics prided themselves on being the smarter, tougher, harder-playing team, no matter who was in uniform. That identity, established by Joe Mazzulla, has been embraced top to bottom, all the way through Game 82.
With just eight available players for the season finale Sunday — Baylor Scheierman, Jordan Walsh, Luka Garza, Ron Harper Jr., Max Shulga, Dalano Banton, John Tonje, and Amari Williams — the Celtics upset the Orlando Magic, who played their full rotation in hopes of securing homecourt for the 7-8 Play-In Game.
“We said it all year, one through 15, whoever steps on the floor, there’s an expectation to put us in position with an opportunity to win,” Mazzulla said. “Stick to the process of winning. Today is no different than the other 81 games from the standpoint of, we had five guys that were able to play — we had seven, eight guys — and the expectation is to put us in position to win. To execute, to play hard, to play together.”
Four players posted career highs in scoring — Scheierman (30), Garza (27), Harper Jr. (27), and Tonje (13) — in a performance that perfectly captured what this team has been about.
“Today is kind of the perfect example of just the locker and the group of guys that we have, and how important it is that everybody knows that if you’re on the floor, you’re expected to play a certain way, and put us in position to win,” added Mazzulla.
It was a fitting end to a season that embodied a true next-man-up mentality.
Whether it was the veterans — Jaylen Brown, Derrick White, Payton Pritchard, and Sam Hauser — taking on larger roles or younger, unproven contributors like Neemias Queta, Baylor Scheierman, Jordan Walsh, Hugo González, and Luka Garza stepping into theirs, the Celtics stayed consistent. No matter who played, the identity didn’t change, and the results followed.
Boston finished with the league’s second-ranked offense (120.0) and fourth-ranked defense (111.7), outscoring opponents by 8.3 points per possession, the fourth-best mark in the NBA. They ranked fourth in both total wins and point differential, and were consistently competitive night to night, with just seven losses by more than 10 points all season.
“It says everything about the team. They are the ones that have to go out and do it,” Mazzula said. “It just proves that we have really good players. Proves that we have a system. Proves that we have a locker room that cares about winning.”
With Tatum rehabbing and all the roster turnover, that system was tested this season.
It held.
With the organizational alignment in place — from the front office to the coaching staff to the championship core, from the developmental success stories to the stay-ready group that gutted out a win in Game 82 — the Celtics never faltered. They extended their streak to five straight 50-win seasons, the longest active run in the league, and reached at least 56 wins for the fourth time in that span.
Now comes the real test.
As they prepare to open their postseason run next Sunday, there’s plenty of reason to view them as legitimate NBA Finals contenders, especially with the return of Jayson Tatum. Since coming back, the Celtics are 13-3 with him in the lineup, his impact and level of play adding yet another standout chapter to a season already filled with them.
With a week before their playoff run begins against either Orlando or Philadelphia, the Celtics’ regular season deserves recognition. But now the real test begins, the one that carries real weight.
