In a dramatic move that marks an abrupt end of the Big Three era in Boston, the Celtics and Brooklyn Nets agreed in principle to a blockbuster deal that will send Paul Pierce and Kevin Garnett to the Nets, a league source told the Globe Thursday night.
The deal won’t become official until July 10, when a league-wide moratorium on signings and trades is lifted after free agency begins July 1.
But a league source confirmed that Garnett agreed to waive his no-trade clause, meaning the massive deal has cleared perhaps its toughest hurdle.
Though the Celtics will part with two of the franchise’s best and most popular players, the deal represents the front office’s plans to aggressively rebuild the roster.
A league source stressed that the particulars to the deal are fluid, but under the proposed terms, the Nets would send multiple players and at least three first-round draft picks (in 2014, 2016, and 2018) to the Celtics.
The Celtics are set to have nine first-round draft picks over the next five seasons.
Among the Nets players in the proposed package coming to Boston: Gerald Wallace, Kris Humphries, Tornike Shengelia, Reggie Evans, Kris Joseph, and Keith Bogans.
And the Celtics plan to ship guard Jason Terry to the Nets, as well.
In all, the ability to acquire first-round draft picks, highly coveted under the NBA’s new collective bargaining agreement that constricts teams’ financial resources, gives the Celtics extremely valuable assets with which to rebuild.
The Celtics had already acquired an unprotected 2015 first-round draft pick from the Clippers in exchange for allowing Doc Rivers to escape his coaching contract with the Celtics, which had three remaining seasons on it worth $21 million.
And by trading Pierce and Garnett, as well as Terry after only one season in Boston, the Celtics will also clear considerable cap space that will further help their rebuilding efforts.
The Celtics were facing a hard deadline with Pierce, the franchise’s No. 2 all-time scorer.
Come Sunday, the Celtics either had to buy out Pierce’s contract for $5 million or his $15.3 million contract for next season was guaranteed.
As for Garnett, who joined the Celtics in a 2007 trade with Minnesota, it wasn’t clear whether the former MVP would return to Boston or perhaps retire after Rivers left.
By trading both Garnett, 37, and Pierce, 35, though, the Celtics no longer have to wait for answers about the futures of their two most iconic players on the roster.
Now, the Celtics know where both are heading — and they’re receiving plenty in return.
“I knew it was coming,” Rivers told reporters in Los Angeles. “Danny [Ainge] and I had talked about that over the last 3-4 weeks. I knew all this was going to happen. It’s obviously sad whenever an era or time ends, and it has now. That’s the sad part.”
For the Nets, the deal would give them two future Hall of Famers to help bolster their roster under Jason Kidd, a first-year coach.
Kidd is just three years older than Garnett and entered the NBA one year before him.
Garnett and Pierce, who have been friends since they were teenagers, will also remain united, no doubt a key reason Garnett agreed to waive his no-trade clause.
Ainge, the Celtics’ president of basketball operations, spoke to the media before terms were agreed upon, and didn’t comment on the proposed trade.
However, Ainge did touch on the subject of rebuilding the Celtics.
“We are in a much better position than we were when I got here 10 years ago, when we sort of had to do it in pieces, and move at a slower pace,” Ainge said. “Our objective is to do it less painful, and with more speed, more pace.”
Ainge was also asked if he was comfortable building a team around mercurial All-Star point guard Rajon Rondo. “Yes, yes we are,” Ainge said.
Is everyone on the Celtics tradeable? Ainge paused before answering.
“If Wilt Chamberlain and Kareem Abdul-Jabbar are tradeable, I guess everybody is tradeable,” he said. “There’s guys we’re not looking to move right now.”
Ainge said Rondo was one of those players.
The Celtics’ Big Three brought Boston an NBA championship in 2008, and nearly another in 2010, but it lost a key piece in the summer of 2012 when Ray Allen signed with the Miami Heat.
Now, those other two pieces — the remaining soul of the team — are gone, too.
So ends an era in Boston, another in a long line of glorious years in the team’s history.Baxter Holmes can be reached at email@example.com. Follow him on Twitter at @BaxterHolmes