Tyler Zeller called his 2015-16 "frustrating" due to inconsistent playing time.
Brad Stevens said he was "thrilled" that the Celtics were able to re-sign Tyler Zeller.
Tyler Zeller's minutes in Boston this season will likely be "infrequent."
Tyler Zeller signed his deal with the Celtics on Wednesday.
Tyler Zeller has agreed to a two-year, $16 million deal with the Celtics.
Steve Bulpett of the Boston Herald does not believe RFA Tyler Zeller will re-sign with the Celtics.
The Celtics have reportedly extended a qualifying offer to Tyler Zeller, making him a restricted free agent.
Tyler Zeller scored a career-high tying 26 points on 9-of-15 shooting Friday, to go with three boards, two assists and four blocks in 25 minutes.
Tyler Zeller scored four points with six rebounds and one turnover in 18 minutes against the Jazz on Friday.
Tyler Zeller played only six minutes off the Celtics' bench on Wednesday.
Coach Brad Stevens called Tyler Zeller a "stable presence at the rim."
Tyler Zeller scored a season-high 17 points vs. Sacramento on Sunday, sinking 6-of-8 FGs and 5-of-5 FTs with seven rebounds, two blocks and one assist.
Tyler Zeller scored 16 points on 8-of-10 shooting Friday, to go with four boards, one assist and three turnovers through 20 minutes of action.
Tyler Zeller, who went off for his best game of the season on Tuesday, played just 14 minutes on Wednesday.