The source said the Celtics will also send the Bulls the best of their four second-round picks this season, and will receive the Nuggets’ 2027 second-round pick the Bulls had previously acquired.
The source said that although the sides agreed to the deal Tuesday afternoon, it would likely not be officially finalized until Thursday, with the sides keeping avenues open for potential minor tweaks or expansions to the deal. At 4:13 p.m on Tuesday, the Celtics updated their injury report to say Simons would miss Tuesday night’s game against the Mavericks because of personal reasons.
Get Starting Point
A guide through the most important stories of the morning, delivered Monday through Friday.
According to the source, the Celtics are still engaged in trade discussions with teams across the league in advance of Thursday’s 3 p.m. deadline
The source said Vucevic will be acquired using the trade exception the Celtics created when they traded center Kristaps Porzingis to the Hawks last summer. This path helped the team create a new $27.7 million trade exception that will not expire until next season’s trade deadline.
The source said the Celtics were thrilled with the production of Simons, who embraced a bench role after being acquired in the Jrue Holiday trade last summer. But the team was focused on strengthening its frontcourt, and the looming return of Jayson Tatum would likely make up for the scoring punch lost by Simons’s departure.
There is increasing speculation the move is a confirmation Tatum plans to return this season. He was in Dallas with the team and conducted a personal workout after the team’s shootaround at American Airlines Center.
Tatum also posted a video of himself deadlifting more the 400 pounds this weekend as he continues his rehabilitation from a torn Achilles.
The source said Vucevic has been on the Celtics’ radar for years, dating back to his time with the Magic, when Danny Ainge was still the Celtics’ president of basketball operations.
The two-time All-Star is averaging 16.9 points and 9 rebounds this season and is a good passer. And following the offseason departures of floor-spacing big men Al Horford and Porzingis, the Celtics will add one of the best in that area. Vucevic is shooting 37.6 percent from the 3-point line this season.
Like Simons, Vucevic is on an expiring contract, earning $21.5 million this season. In addition to paying a smaller salary, the Celtics will reduce their luxury tax bill by about $22 million with this move, and push it below the salary cap’s first apron, opening some new roster-building tools.
The Celtics now have three reliable big men, with Vucevic, starting center Neemias Queta, and backup center Luka Garza, who has emerged as a key piece in recent weeks.
Simons, who poured in 27 points in the Celtics’ 107-79 win over the Bucks on Sunday, is averaging 14.2 points while shooting 39.5 percent from the 3-point line.
The Celtics were severely shorthanded against the Mavericks with Simons and Chris Boucher, another potential trade candidate, out of the lineup. But the team was aware of the deal and lamented the absence of a popular player in the locker room.
The player who could be most affected by the trade is Queta, who could share frontcourt duties with Vucevic or play alongside him in a two-big lineup. Queta’s locker was also next to Simons’s and the two grew close during the season.
“It’s always tough to see one of your teammates go,” Queta told the Globe. “He was really mild-mannered, really well-spoken. I think he was one of the great additions we had in the last couple of years. It’s always tough to see him go, especially as a friend. We were always chatting it up. I’m going to miss him [being] around, but that’s the nature of the business.”
Queta said he can learn from the 35-year-old Vucevic and looked at his addition as a growth opportunity.
“[Vucevic] has been in the league for so long; he’s been a multiple time All-Star,” Queta said. “He brings a bunch of different stuff for us. Just having that veteran leadership as well, just asking questions and trying to learn from him as well as best I can. Obviously, we can play double big together or go one at a time. We’ll figure that stuff out and I’m just here to make his transition as seamless as possible.”
Gary Washburn of the Globe Staff reported from Dallas.
Adam Himmelsbach can be reached at adam.himmelsbach@globe.com. Follow him @adamhimmelsbach. Gary Washburn is a Globe columnist. He can be reached at gary.washburn@globe.com. Follow him @GwashburnGlobe.