Boston Celtics v Dallas Mavericks
DALLAS, TEXAS - Luka Doncic (#77) of the Dallas Mavericks drives to the basket against Grant Williams (#12) of the Boston Celtics in the second half at American Airlines Center on January 05, 2023 in Dallas, Texas. Tom Pennington/Getty Images

The Boston Celtics have unloaded another defensive anchor as it lose restricted free agent Grant Williams in a three-team trade that involves the San Antonio Spurs and the Dallas Mavericks.

Who got who?

Williams will join the Mavs on a four-year, $54 million contract.

Dallas let go of Reggie Bullock, who will join the Spurs, and an unprotected Dallas pick swap in 2030.

Celtics will receive multiple second-round picks.

This development is different from what Celtics envisioned for a Williams deal. Jared Weiss of The Athletic first reported that Brad Stevens sought first-round picks to let go of Williams.

The 6-8 forward is an integral part of the Celtics' core that competed for the title. He is among the designated primary defender against opponents' best players.

Dallas will have to wait for Williams as he enters rehab after having surgery on his injured left hand. He played 79 games last season and averaged 8.1 points, 4.6 rebounds and 1.7 assists.

Williams is a sacrifice

Weiss also previously reported that Williams might be crucial to the team, but he has to be sacrificed to keep Jaylen Brown and meet the collective bargaining agreement requirements.

Brown and the Celtics have yet to agree on a new deal. With Williams' contract settled, negotiations for a designated veteran extension will follow soon.

"Brown can make 35 percent of the cap as a designated veteran as opposed to just 30 percent for the rookie supermaxes," Weiss wrote in The Athletic.