Photo: Instagram/Grant Williams In a noteworthy three-team sign-and-trade agreement, the Dallas Mavericks have secured the services of restricted free agent forward Grant Williams on a lucrative four-year contract worth $54 million. Reliable sources have confirmed the details of this deal, which involved the Boston Celtics and the San Antonio Spurs as well. As part of the arrangement, the San Antonio Spurs will acquire forward Reggie Bullock from the Mavericks along with an unprotected first-round pick swap set for 2030. In return for their involvement, the Boston Celtics will be receiving multiple second-round draft picks and a valuable $6.2 million trade exception. Grant Williams, a first-round pick from Tennessee in the 2019 NBA Draft, has been a part of the Celtics organization for the past four seasons. Photo: Instagram/Grant Williams During the previous season, he showcased his skills by averaging 8.1 points, 4.6 rebounds, and an impressive 39.5% shooting accuracy from beyon...