Brad Stevens keeping Joe Mazzulla, calls Jaylen Brown 'big part' of Celtics

Brad Stevens stands by Celtics coach Joe Mazzulla (2:26)

Brad Stevens is confident in Joe Mazzulla and his future as the Celtics coach. (2:26)

Joe Mazzulla remains head coach of the Boston Celtics and will return next season, team president Brad Stevens said Thursday.

"He's a terrific leader," Stevens said. "He'll only get better at anything that he can learn from this year, because he's constantly trying to learn. And he's accountable."

Mazzulla, 34, led the Celtics to a 57-25 record and the No. 2 seed in the Eastern Conference in his first season on the bench. Boston's season ended Monday with a Game 7 loss to the Miami Heat in the East finals.

Mazzulla took over when coach Ime Udoka was suspended for the season in September for multiple violations of team rules. He reportedly had an intimate relationship with an unidentified female staff member.

Three Celtics assistant coaches -- Ben Sullivan, Aaron Miles and Mike Mose -- are reportedly leaving to rejoin Udoka, who was named head coach of the Houston Rockets last month.

Stevens said the Celtics do plan to add at least one assistant coach with extensive NBA experience on the bench this summer, filling the spot vacated when Damon Stoudamire left to become Georgia Tech's coach in March.

As far as changes to the roster, Stevens said while they will always monitor the league landscape for potential additions who could help, he likes his team's existing core.

Due to NBA rules that restrict what executives are allowed to say about players with pending contracts, Stevens declined to speak specifically on the decisions needed to be made this offseason involving Jaylen Brown (eligible to sign a five-year supermax extension July 1) and restricted free agent Grant Williams.

"I've had nothing but great conversations with Jaylen," Stevens said. "I can say, without a doubt, we want Jaylen to be here. He's a big part of us. We believe in him and I'm thankful for him. ... I'm really thankful that when those guys have success they come back to work. And when they get beat, they own it and they come back to work. And so I know that's what they're about. And that's hard to find."

Stevens believes Williams got caught in a numbers situation regarding his reduced time in the rotation this season.

"He is a good player who was on a really deep team," Stevens said. "With the addition of [Malcolm] Brogdon last year, it was going to require that guys that had gotten a little more opportunity weren't going to get as much. That obviously hit a few of our players. ... But everybody around the league knows Grant can add value to any team."

Whatever happens, Stevens said, it will start with doing as little as possible to disrupt the infrastructure of a team he believes has the bones to be a championship team.

"At the end of the day we love our foundation. We love our core. And that's really our focus and our priority," Stevens said.

Information from Reuters and The Associated Press was used in this report