Brissett declined his $2.5 million player option with the Celtics on Sunday, Keith Smith of Spotrac.com reports.
Brissett will become an unrestricted free agent after declining his player option Sunday. The 26-year-old spent one season with the team, and he averaged 3.7 points, 2.9 rebounds, 0.8 assists and 0.3 steals across 11.5 minutes in 55 regular-season games. Brissett was a non-factor for Boston in the playoffs, and his departure likely signals a desire for a larger role elsewhere.