League sources said last week that the addition of Porzingis, who fortified the frontcourt and added another hefty salary to the books, would make Grant Williams’s return unlikely, especially considering that a big deal for Williams could send Boston past the $182.7 million second apron that activates further roster-building restrictions
Since Williams is a restricted free agent, Boston will have the option of matching any offer sheet he signs with another team, and a league source said Friday that the Celtics were mostly waiting for that to occur before being compelled to take their next step. – via Boston Globe