Joe Mazzulla has been called weird. He's been called a "sicko". He's been called crazy.

Those comments weren't coming from critics or haters directing anonymous insults toward the coach of the Boston Celtics. They came publicly from his own players who, by all accounts, absolutely adore him. And they are meant with all possible respect, especially now that those players — and everyone else — must call Mazzulla something else.

A champion.

A 35-year-old, whose only head coaching experience before taking over the Celtics in the fall of 2022 was at the NCAA Division II level, is now the leader of the best team in the NBA. Boston wrapped up the NBA title on Monday night, beating the Dallas Mavericks 106-88 to finish off a five-game roll through the finals and secure the team's record 18th championship.

"There's nothing better than representing the Celtics," Mazzulla said, "and being part of history."

Including playoffs, Mazzulla's record is now 148-54 — a .729 winning percentage. Among all coaches with at least 200 games in the NBA, nobody has a better record than that.

And when it was over, yes, the famously stoic Mazzulla smiled.

"The thing you just can't take for granted in the game today is a coach's greatest gift — a group of guys that want to be coached, want to be led, that also empower themselves," Mazzulla said earlier in the series. "So, I think at the end of the day, just appreciate the fact that we have an environment where learning and coaching is important, and getting better and developing is important. You can't be a good coach if your players don't let you be one."

He's the 37th coach in NBA history to win a title, and the seventh to do so from the Celtics' bench, joining Red Auerbach, Bill Russell, Tom Heinsohn, Bill Fitch, KC Jones and Doc Rivers.

And there are other names the Celtics call him, too. Like genius, for example. Mazzulla doesn't hide his Christian faith, talks about three of his loves beyond family being Jesus, coffee and jiu-jitsu, is obsessed with things like international soccer, and, in his spare time, leads teams to NBA titles.

"He's really himself. He's, like, authentic to himself. We all appreciate that," Celtics guard Payton Pritchard said. "He's not trying to be somebody he's not. So, I think that's kind of like the sicko side of it. He's different, but we respect that. Then the basketball genius, you can learn a lot from him as to how he sees the offensive side of things, the play calling, the game management, all that. He's elite in that. I've personally learned a lot from him, and I think our whole group has."

Alex Cora, the manager of the Boston Red Sox, makes no secret that he believes the Celtics are going to be enjoying success for a while. He's close with Brad Stevens, the front office mastermind of the team, and has gotten to know Mazzulla somewhat well since he took over as coach. The respect he has for Mazzulla is clear.

It's not like Mazzulla struggled in his first year after being shoved into the job unexpectedly, following the scandal that led to the Celtics parting ways with Ime Udoka; the Celtics did make Game 7 of the Eastern Conference finals last season. Cora just thinks things were more suited to Mazzulla's needs in his sophomore year, such as bringing in assistants like Charles Lee (the next coach of the Charlotte Hornets) and Sam Cassell.

"I do believe that, with everything that they went through, with the head coaching part of it, and Joe last year being the head coach, but not having his staff, I think it was kind of like an obstacle for him," Cora told reporters before a Red Sox game last week. "But, he got the right people, they got the right coach."

Mazzulla's path to the NBA mountaintop could easily be described as non-traditional, and not just for the circumstances under which he got the job as Udoka's replacement.

Mazzulla's only previous experience as a head coach before taking over the Celtics was a two-year stint at Fairmont State in West Virginia, where he went 43-17 and made the NCAA Tournament in his second season. A native New Englander from Rhode Island, Mazzulla played at West Virginia, was an assistant for the Celtics' G-League team before taking over at Fairmont State, and then got hired by the Celtics again in June 2019 to be part of Stevens' coaching staff.

They're a lot alike, Mazzulla and Stevens. They don't waste words. They don't seek the spotlight. Asking them a question about themselves is almost certainly not going to get any sort of peel-back-the-curtain answer. It's not about them. It's just about wins.

"When Joe won coach of the month, I was like, 'hey, congratulations,'" Celtics guard Derrick White said. "And he just looked at me and said, 'Nobody cares.'"

The closest Mazzulla likely came to getting a head-coaching gig in the NBA before getting promoted by Boston was in 2022, when he interviewed with the Utah Jazz. The Jazz hired Will Hardy, and Mazzulla said they made the right decision. But, when he looked back at that process, Mazzulla hated one part of his interview.

He wore a suit. "They're useless," he said.

To be clear, that wasn't where Mazzulla thinks he blew that interview. The Jazz asked him a fairly standard question. Paraphrasing, they wanted to know how Mazzulla, as a young coach — actually younger than some NBA players — felt he was ready to lead a team.

He didn't have a great answer. But now, nobody will have to ask him that question again. Mazzulla answered it Monday night once and for all. He can lead a team to the top of the NBA. The Celtics' 18th banner will be raised this fall, and that's more than enough for him.

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