Boston’s Jayson Tatum, left, celebrates next to Celtics co-owner Stephen Pagliuca, right, near the Larry O’Brien Championship Trophy after the Celtics won the NBA title with a Game 5 victory over the Dallas Mavericks on Monday in Boston. Charles Krupa/Associated Press

BOSTON — It took more than a decade, savvy front office and draft moves, and some free agency luck for the Celtics to ultimately build the roster that brought an end to their 16-year championship drought.

But with NBA Finals MVP Jaylen Brown already locked up long-term and fellow All-Star Jayson Tatum set to join him in the $300 million club this summer, Boston doesn’t have nearly as much work to do this offseason to keep together a core that is set up to become the first team since the 2018 Golden State Warriors to repeat as champions.

In the euphoria of locking up the franchise’s record-breaking 18th championship, Celtics majority owner Wyc Grousbeck gave President of Basketball Operations Brad Stevens a shoutout for finishing a process that began when Stevens was originally hired as Boston’s coach in 2013.

“We all watched the team the last few years. Great teams, but not quite there,” Grousbeck said. “And Brad was brilliant. We knew we needed to make changes … and he got it done.”

Moving away from longtime executive Danny Ainge – the architect of Boston’s 2008 championship Big 3 of Paul Pierce, Kevin Garnett and Ray Allen – in favor of the 44-year-old Stevens was bold. Now, just three years after being pulled off the sideline, Stevens has made good on the belief that ownership had in him.

He did it by taking the war chest of draft picks Ainge left him and borrowing from the aggressiveness his predecessor was known for to immediately go to work.

It started coyly with a February 2022 trade deadline acquisition of Derrick White, a young defensive-minded reserve with San Antonio.

Then, following the loss to the Warriors in the Finals, he steered the team through the suspension and ultimate departure of the Celtics coach, Ime Udoka for having an inappropriate relationship with a woman in the organization.

Celtics Coach Joe Mazzulla, center, holds the Larry O’Brien Trophy after Boston beat Dallas, 106-88, in Game 5 of the NBA Finals on Monday in Boston. Charles Krupa/Associated Press

Facing a franchise-altering moment, Stevens leaned on his gut, elevating back bench assistant Joe Mazzulla to the top job.

Then, after a conference finals loss to Miami last season, he did what was originally unthinkable by trading veteran leader Marcus Smart and reigning NBA Sixth Man of the Year Malcolm Brogdon in separate deals that brought in 7-footer Kristaps Porzingis and defensive stalwart Jrue Holiday.

The pair turned out to be the missing links for a team that, including the playoffs, finished 80-21 this season, placing it second in team history behind only the Celtics’ 1985-86 championship team that finished 82-18.

It also marks the first time in seven seasons the team with the best record during the regular season went on to win the title.

Most importantly, Boston is set up to keep the current core intact for the foreseeable future.

Brown is already locked up through 2029. Tatum is eligible to sign a five-year supermax extension this summer that will be worth a record $315 million and run through 2031. White, who is set to be a free agent in 2025, can ink a four-year deal worth about $125 million this offseason.

The remaining returning starters, Holiday and Porzingis, have already been extended through 2028 and 2026, respectively.

While some tough, luxury tax decisions could be looming in a few seasons, it’s a team constructed to win now.

Brown said it’s left everyone poised to defend their title next season and beyond.

“I think we have an opportunity. I think we definitely have a window,” he said. “We take it one day at a time. We definitely have to make sure we stay healthy. But, we’ll enjoy the summer, enjoy the moment, and then we get right back to it next year.”