The Celtics have filled 12 of 15 roster spots, plus both of their two-way slots, currently occupied by this year's second-round draft pick, JD Davison, and former first-round selection, Mfiondu Kabengele.
For Kabengele to play his way into a full-time roster spot, he'd likely have to prove himself in the regular season. However, regarding Davison, as a player Boston drafted who's on his rookie contract, the Celtics would save on the luxury tax by promoting him instead of signing someone who doesn't meet that criteria. A minimum salary for him would count roughly half of what it would for another player.
And when it comes to who Boston might add as another layer of depth at the center position, according to Jay King of The Athletic, while veterans like Dwight Howard are available in free agency, and the Celtics could explore their options on the trade market, there's a belief they prefer younger players with room to grow.
Individuals who fit that description are also likely to be more accepting of a limited role. Keep in mind, Ime Udoka can, and at times will, short shift Al Horford or Robert Williams, making it easier to have one of them on the floor as a game progresses. He can also play Danilo Gallinari at center. While it's less likely, the same is also true of Grant Williams.
Plus, the team re-signed Luke Kornet to a two-year deal this offseason. At the introductory press conference for Malcolm Brogdon and Gallinari, Brad Stevens expressed confidence in the seven-foot-two Kornet's capabilities, saying, "we're really believing in Luke as not only depth to fill out the roster but also be ready to help us."
King also reports that while there's an expectation Boston has an open competition for its final roster spots, Matt Ryan, who signed a two-way deal with the Celtics last season, seems unlikely to be back for a second stint. King adds a league source has informed him Ryan has fully recovered from the ankle injury he sustained at Summer League on the play that he banked in a game-winning three at the buzzer.
While Ryan appears on the move, three former first-round picks will come to training camp to compete for one of Boston's available roster spots. That trio consists of Justin Jackson, who briefly spent time with the Celtics last season and suited up for them in Sin City this summer, and recent additions, Bruno Caboclo and Noah Vonleh. Brodric Thomas, who was on a two-way deal with Boston last season, is also expected to be in the mix.