Perhaps the largest domino of the Boston Celtics’ free agency plans finally fell this week.

Grant Williams is headed to the Dallas Mavericks as part of a three-team deal that also includes the San Antonio Spurs. In it, the Celtics picked up two second-round picks, a 2025 second-round pick swap, and a traded player exception worth about $6.2 million. The Spurs got Reggie Bullock and a 2030 first-round pick swap. The Mavs ended up with Williams and a second-round pick from San Antonio.

The deal ends Williams’ time in Boston after he was selected 22nd overall in the 2019 draft. He had a rocky start for the Celtics, missing plenty of 3-pointers, but he developed into a rotation player who made an impact the past few seasons. But Williams was looking for his payday, and the Mavs offered a four-year, $54 million contract to land the 6-foot-6 forward.

The Celtics have made major roster changes over the past few weeks, shipping Marcus Smart to the Grizzlies and now getting some assets back in a Williams deal. They also obtained Kristaps Porzingis and a bunch of second-round draft picks. In free agency, they have signed forward Oshae Brissett and guard Dalano Banton.

It’ll be interesting to see if the Celtics continue tweaking the roster. If they want to swing big for a star, they do have some assets to make that happen. They could revisit a Malcolm Brogdon deal, as he was almost shipped out in exchange for Porzingis, only for that trade to fall apart before they eventually relinquished Smart. Regardless, the Celtics traded away some of their depth in Williams, though keeping him at that price would have been difficult considering salary cap constraints. It also was difficult to see how Williams fit into the roster going forward. He fell out of favor at times amid some struggles last season, and his playoff minutes were inconsistent under Coach Joe Mazzulla. Williams had his moments, but there were times where he was ineffective.

After the Celtics picked up Porzingis, the front court got even more crowded. Porzingis, Robert Williams III and Al Horford make up what should be a strong front court.

The Celtics, though, lost a depth option in case of any injuries. Porzingis and Rob Williams both have injury-prone histories, while Horford just turned 37. So while those three are plenty talented, durability is a question mark over a long regular season and what the Celtics hope will be another deep playoff run.

On the flip side, the Celtics can still upgrade their bench with playable big men who can give regular-season minutes. Brissett could pick up wing minutes, and Sam Hauser could also see an expanded role. Grant Williams, at this point, is a luxury for the Celtics to have as a backup big man. With the new CBA and the payroll constraints, the Celtics elected to use money and resources elsewhere.

There are going to be more opportunities for Williams to play with the Mavericks. He shouldn’t demand many touches and can space the floor for star Luka Doncic, who will get him open looks. Along with getting his payday, Williams appears to have ended up in a favorable playing position.

The Celtics did lose defensive juice this summer, though. Smart, the NBA’s 2021-22 Defensive Player of the Year, was a key piece of that equation and was a vocal leader. Williams also provided toughness on that end, and his defensive versatility was often praised. He was far from a perfect defender, but ended up being a solid option on opposing stars like Giannis Antetokounmpo. At the offensive end, Williams shot 40.3% from 3 the last two seasons.

Boston President Brad Stevens and the front office have shaken up the roster less than a week into free agency. How the Celtics operate going forward will be interesting. But the major moves appear to have been made, though there’s plenty of offseason still left.