Williams is enjoying life in the Lone Star

DALLAS — Jayson Tatum was addressing the media after Friday’s loss to the Denver Nuggets. As he stepped to the podium, he mouthed to his phone, “I’ll call you right back,” then began his interview.

“When he picked up the FaceTime, I was like, ‘Oh I’m sorry, I didn’t know you were on the phone,’ ” a laughing Grant Williams said. “I didn’t mean to. I was like, ‘All [expletive], my bad J.’ ”

Williams shot just 1 of 5 from the field Monday, with 3 rebounds and 2 assists in 18 minutes at American Airlines Center. He keeps in constant touch with Tatum, Sam Hauser, and Payton Pritchard. The affable, talkative forward helped the Celtics to three Eastern Conference finals and enjoyed his share of notable moments before he was traded to the Mavericks in July as the Celtics reshaped their roster.

Williams wanted to remain in Boston, but also relished the chance for more playing time and a more defined role. He said he has no issues with the trade and enjoys the new scene in Dallas.

“I love the city, love the people. Very, very fortunate to be in Dallas and for them to trust me and bring me here,” he said. “I very much enjoy the home that I purchased and the life that I’m living. Just trying my best to perform for the opportunity.”

Williams played four years for the Celtics and experienced his ups and downs, but there were times he flourished, such as when he hit seven 3-pointers in the Game 7 win over the Bucks in the 2022 Eastern Conference semifinals. He was a useful piece, but as restricted free agency approached, the Celtics had other financial obligations.

They didn’t want to invest nearly $50 million over four years in Williams, especially since they had to pay Jaylen Brown, Tatum, Kristaps Porzingis, and, eventually, Derrick White. Dallas had been interested for years in Williams, a staunch defender and fearless competitor.

A member of the NBA Players Association Executive Committee, Williams said he understood the business. He helped negotiate the most recent collective bargaining agreement, which includes the infamous second apron salary cap level that the Celtics approached with all their offseason moves. Williams knew he was likely the one who wouldn’t return after the team’s playoff elimination by the Heat.

“You have to understand the business side of things, especially with the direction the team wanted to [go],” Williams said. “I feel like at the time, we were right at that edge of competition and didn’t get over the hump with the group that we had, and it’s bound to happen. It’s a matter of, you want to keep people there that are completely in, and I think that’s how they have to approach it. They have to approach it like, we have to do what’s best for the organization, maybe if it’s not best for the player.”

Williams said he used to joke with vice president of basketball operations Mike Zarren, telling him he didn’t want to get traded for just one second-round pick. Second-round picks are generally exchanged when one team wants to dump a player’s salary on another.

In a three-team deal, the Celtics acquired three second-round picks for Williams.

“Zarren always used to get mad at me when I used to bring up trades,” Williams said. “I played makeshift GM sometimes and that’s fun to be. I don’t feel like it never bothered me in that regard.”

In Dallas, Williams has started 27 of 39 games, but is playing about the same 27 minutes he did with the Celtics. Prior to Monday, he was averaging 8.2 points (compared with 8.1 last season) and shooting 36.9 percent from the 3point line. Coach Jason Kidd moved Williams to the bench in late December; he’s slumped in that role, shooting 24.2 percent from three as a reserve before he missed all four of his tries Monday.

“You’re asked to do a little bit more, be a little bit more aggressive offensively,” Williams said. “Shoot the open shots when they are available, continue to defend at a high level, as I did in Boston. You try your best to make an impact, you have a lot more opportunity to create.”

Williams has had to adjust to playing with two ball dominant guards, former Celtic Kyrie Irving and All-NBA point guard Luka Doncic.

“Spacing is the No. 1 priority, and just making sure you have a relationship with those guys,” he said. “You have to be mindful and keep your mentality of what they want and expect of you. That way, you can perform to the best of your ability as well.”

Porzingis gets a rest

The Celtics held Porzingis out Monday with what they called knee inflammation — essentially, it’s a rest day. Porzingis, who scored 32 points in Sunday’s win, is expected to play Thursday at Miami. The club also made Oshae Brissett a late scratch with a lower back strain. It’s uncertain when Brissett suffered the injury. That could mean more minutes for Lamar Stevens in the coming days . . . The Mavericks were without sharpshooter Seth Curry (left ankle sprain) and Dante Exum (right plantar strain). They were playing for the first time in five days after Friday’s game against the Warriors was postponed because of the death of Golden State assistant coach Dejan Milojevic.