Reports: Grant Williams leaving Celtics for Mavericks via $53 million ...

Grant Williams is leaving the Boston Celtics for the Dallas Mavericks in a three-way trade involving the San Antonio Spurs, The Athletic's Shams Charania reports.

Per ESPN's Adrian Wojnarowski, Williams, a restricted free agent, agreed to a four-year, $53 million contract to facilitate the sign-and-trade deal. The Spurs will receive Reggie Bullock and an unprotected 2030 pick swap with Dallas in return. The Celtics will receive multiple second-round picks.

Williams, 24, has played his entire four-season NBA career with the Celtics since they selected him with the No. 22 pick of the 2019 draft. A 6-foot-6 forward who played primarily off the bench, Williams averaged 8.1 points, 4.6 rebounds and 1.7 assists while shooting 45.4% from the floor and 39.5% on 3.7 3-point attempts per game last season.

Williams joins a Mavericks team that's extended guard Kyrie Irving and acquired center Richaun Holmes this offseason in addition to drafting Duke center Dereck Lively II and Marquette forward Olivier-Maxence Prosper. They've also reportedly submitted an offer sheet to Portland Trail Blazers restricted free agent Matisse Thybulle, a defensive stopper who fills a need.

The Mavericks have remained in need of depth, shooting and defense after trading Spencer Dinwiddie and Dorian Finney-Smith in the midseason deal to acquire Irving. They went from playoff position to out of the postseason after making the trade. Williams is a catch-and-shoot threat from the corner and has proven himself as a more-than-capable defender with the Celtics.

His exit from Boston continues a roster shift following a disappointing Eastern Conference finals loss to the No. 8 seed Miami Heat. The Celtics traded longtime point guard Marcus Smart to the Memphis Grizzlies in a three-way deal to acquire Kristaps Porziņģis. The trade of Williams opens up salary cap flexibility as the Celtics and All-Star forward Jaylen Brown remain without a long-term extension.