• Download the NBA App

BOSTON — Turning 18 is usually a sign of maturity, of finally growing up. In typical situations, at least.

Then why did the Boston Celtics players dance on the confetti-covered TD Garden floor in the late Monday hour like kindergarten kids? Why was their star, Jayson Tatum, reduced to tears as he went from teammate to teammate, squeezing the breath out of them?

“I’m sorry,” said Tatum, who really wasn’t.

No need to apologize for the emotion. The Celtics won the 18th championship in their storied history with a breezy if not easy dismissal of the Dallas Mavericks, 106-88. The NBA Finals presented by YouTube TV lasted five games, and the elimination game was secured almost from the start.

And yet … there was a sense of relief, if not surprise, that swept over players and coaches. That was the reason for all the laughter and the exhale and widespread joy. Such is the case when you finish what you started and avoid all the traps along the way.

“It was a joy watching the guys just grow as a team throughout the year but also like really work at it,” said Celtics coach Joe Mazzulla. “A group of guys in the locker room that decided they wanted to win from day one, and credit to them.”

The Celtics are back in the business of winning championships. That’s baked into their tradition, a franchise now with titles in six different decades.

This means the Celtics not only won championships in your grandfather’s day and your father’s time, but also present day. At least three generations of basketball fans can say they saw this team raise a banner.

Eighteen titles is the most in NBA history, one more than Boston’s rival, the Los Angeles Lakers. The latest one represents the about-time achievement of Tatum and Jaylen Brown, a pair of career Celtics swingmen who, until Monday, did everything in a Celtics’ uniform except sip champagne.

But this entire team offered so much more. Smartly assembled by front office boss Brad Stevens, the Celtics had star power and also depth, which made them tough at both ends and able to win even with relatively mild production from Tatum and Brown.

Here are the final five takeaways of how the Celtics pursued and secured No. 18:

1. Dominance always on display

The Celtics won 64 times in the regular season, leading the league … and then went next level when it mattered most. That’s because the postseason was a complete and total flex, with only three defeats spread over four rounds.

It was a tip-to-buzzer display that will be recognized by history and reflect well when measuring these Celtics with the best teams of this era.

Given how they went scorched-earth from October through June, perhaps the Celtics’ biggest threat all along was … themselves?

The anticipation this season was steep for a team with a pair of certified stars and layers of solid and dependable players. And the Celtics never wavered from the weight of expectations. They met it, actually.

They won with and without Kristaps Porzingis, their oft-injured 7-foot-3 center who staggered through the season and then missed roughly a month of the postseason. They executed a first-round dismissal of the Heat in five games — a team that bedeviled them in the conference finals last season. Then the Cavaliers were ousted in five games. Then a sweep of the Pacers.

Yes, there was a bit of good fortune (shamrock?) along the way. Jimmy Butler, Donovan Mitchell and Tyrese Haliburton, among others, missed all or chunks of the playoffs. But such is the case with many champions. You must be both lucky and good to raise the trophy.

That shouldn’t dilute what the Celtics just did, because again, they ruled the NBA from the start.

And the best part?

“No drama anywhere,” Stevens said. “It’s been a special group.”

2. Tatum and Brown for the crown 

The Celtics clinched the championship Monday in a manner that defined the essence of this team — lots of Tatum and Brown, who combined for 52 points, 16 rebounds and 17 assists.

They went all tag-team, taking turns burying the Mavericks and sealing that team’s doom. Tatum broke free from a series-long pair of handcuffs and finally had a fluid night shooting the ball. There was a third-quarter stretch where he went iso and felt … free.

Drafted in back-to-back years, Tatum and Brown had to grow together, learn each other’s tendencies and find common ground before they could soar. And even after they became a dangerous tandem, the ultimate reward avoided them.

This championship represented a goal that, until now, proved slippery — Tatum and Brown appeared in six conference finals together. This was their second NBA Finals.

And finally, their first title together.

“Over the last couple years, we had some tough losses at home in the playoffs,” Tatum said. “So I felt like that was really important to go out there and do everything in my power to make sure we won this game tonight.”

Brown was the more consistent player, not only in this series, but the Eastern Conference Finals as well. Getting buckets and guarding Luka Doncic requires plenty, and Brown never ran out of fuel on his way to being awarded the Bill Russell Trophy for Finals MVP.

“I think we learned from all of our mistakes,” Brown said. “All of our adversity has made us stronger, tougher. All season you could see it. We started from the jump. We made all the sacrifices. We played both ends of the ball at a high level. We didn’t skip any steps. And this was the result.”

3. A salute to Stevens 

The MVP — Most Valuable President — of the Finals was a landslide winner, no questions asked and all of them answered.

Let’s just say Red Auerbach is in hoop heaven saluting Brad Stevens with a lit stoogie. That’s how meticulous and marvelous Stevens was in building this team around Brown and Tatum. Stevens made moves that brought the goods — shooting, defense, leadership, depth, the whole nine.

Stevens is at the top of his profession, quite an ascent from someone who transitioned from coaching.

“It’s a lot easier to build a team if you can start with Tatum and Brown,” Stevens said. “We’re just trying to accentuate their strengths. Jrue Holiday, Al Horford, Derrick White, Kristaps Porzingis, we’re lucky they’re here.”

The chef’s kiss was Holiday, acquired last summer. Who knew he’d be the Portland Trail Blazers guard who’d get traded to a contender and win a title? Somewhere in Milwaukee, Damian Lillard ain’t laughing.

Holiday replaced the defense the Celtics lost when they traded Marcus Smart and brought championship sensibilities from winning a title with the Bucks in 2021. Porzingis was a 20-point scorer who recovered from injuries with two big Finals games. Derrick White hit big shots and Al Horford anchored the frontline.

Stevens said the championship reflected the team as a whole, not one or two parts.

“We say all the time, everybody has a role to play and be a superstar in your role, from Jayson Tatum or our analytics department,” Stevens said. “My happiness always comes from the players and the staff and seeing them celebrate. I always like to see them enjoy this, whether you’re a coach, in the equipment department or a chef. Anyone part of the organization.”

Oh — and a special shout-out to former president Danny Ainge for that 2013 trade that keeps on giving — sending the bones of Kevin Garnett and Paul Pierce to Brooklyn for the picks that fetched Tatum and Brown.

4. A more mature Mazzulla makes a difference

The only questionable decision made by Stevens was elevating an assistant coach with no NBA head coaching experience. But, an explanation: When the Celtics parted ways with Ime Udoka in the fall of 2023, right before camp, most if not all of the unemployed candidates were gone.

So Stevens went with his gut and gave the job to Mazzulla, who knew the personnel but dealt with growing pains anyway. Those proved costly in the 2023 Eastern Conference Finals, where the Celtics lost to the lower-seeded Heat.

“I feel like it’s going to be like that for the rest of my career, as it should be,” said Mazzulla of the skepticism. “You need expectations. All those things go into making who you are as a person. If someone tells you ‘Good job,’ that’s just as dangerous as someone telling you you (stink). You need both of them in order to get to where you want to get to, and there’s no place else I’d rather be.”

Mazzulla, who turns 36 in two weeks, owned up to his rotational and strategy mistakes. He hired Sam Cassell for the bench and pressed all the right buttons, or enough of them anyway.

“We knew going into last year it was not going to be an easy transition,” Stevens said. “And we thought he knocked it out of the park, and he was even better this year. He’s going to be a great coach for a long time.”

Handed the keys to a Porsche Turbo, he didn’t steer it off a cliff. When Tatum left Monday’s game with just over a minute left, he went straight to Mazzulla with a bear hug — the best thank you a coach can ever receive.

5. The championship was never in doubt

The Mavericks won a game, emphatically at that. They had a chance in another. But at no point did the feel of this series favor them. This was Boston’s to lose. And the Celtics were too good to allow that to happen.

When they needed a basket, they turned to Brown. A defensive stop? Holiday. A big shot? White. Someone to create for others? Tatum refused to be swallowed up by his shooting slump. And other players fell in line.

A half-court heave to beat the halftime buzzer? That chore belonged to Payton Pritchard, who made two in the series.

All the key moments, plays, rebounds, buckets and stops trickled, then avalanched for the Celtics. Before long, Game 5 was a wrap. The championship was a snap.

“Man, I never forget what Danny Ainge told me,” Horford said. “He said, ‘You can win championships in many places, but there’s nothing like winning in Boston. Nothing like winning as a Celtic.’ And that stuck with me.”

It has stuck with everyone associated with the 2023-24 Celtics. They are now 1 of 18. Built for a banner.

* * *

Shaun Powell has covered the NBA for more than 25 years. You can e-mail him here, find his archive here and follow him on X.

The views on this page do not necessarily reflect the views of the NBA, its clubs or Warner Bros. Discovery.