The Celtics have their midlevel exception available to sign the 34-year-old Miller, who has the versatility to play the power forward and center positions. Several contenders are expected to pursue Miller, but sources say the chance to play for the defending Eastern Conference champions has significant appeal to him.
The departure of Wallace clears $13 million off the Celtics' books over the next two seasons and leaves them with a gaping hole on their frontline. Perkins tore ligaments in his right knee in Game 6 of the NBA Finals and faces a lengthy rehabilitation process.
Despite durability issues during his career, Miller played 82 games for the Chicago Bulls last season and could give the Celtics a rugged presence with an inside-outside offensive game.
The Celtics are still confident coach Doc Rivers will return for the final year of his contract, and he plans to make a decision this week on whether he will be back or join his family in Orlando.
Rivers has acted like a coach who plans to return. He participated in the Celtics' draft preparation, and he had been working with general manager Danny Ainge to prepare for the start of free agency on Thursday. He has also had conversations with prospective candidates to replace Tom Thibodeau on his coaching staff, but that hire is on hold.
Rivers had meetings planned with close associates this week to discuss his future. He also traveled to San Antonio over the weekend to watch his son, Austin, one of the best high school players in the country, compete for USA Basketball in an under-18 tournament.