BOSTON – A younger Jayson Tatum would’ve let his shooting struggles bother him so much that it negatively impacted other parts of his game.

Maybe even Jayson Tatum of a year ago.

But not today’s Jayson Tatum.

Tatum, the Boston Celtics' star forward, is wiser, with his mind fixated on what matters – winning a championship.

The 26-year-old All-NBA forward is not shooting the ball well in the NBA Finals against the Dallas Mavericks. He is 12-for-38 (31.6%) from the field and 28.6% on 3-pointers and averaging just 17 points while committing 4.5 turnovers per game through the first two games of the Finals.

However, he is also averaging 10 rebounds and 8.5 assists, and the Celtics are 25 points better than Dallas with Tatum on the court.

He impacts the game in ways that don’t include scoring – with his passing, rebounding and defending – and the Celtics have a 2-0 series lead after Sunday’s 105-98 victory against Dallas.

"It has a lot to do with that I've been here before and we didn't win, and it's just like, we're so close to what we're trying to accomplish, why would I let my ego or my need to score all the points gets in the way of that," Tatum said. "There are going to be times where I need to score, and obviously, I need to shoot better, golly.

"But you know, really, we always talk about do whatever it takes for however long it takes. If I need to have 16 potential assists every single night and that's what puts us in the best position to win and it doesn't mean I'm the leading scorer, by all means, if that gives us the best chance to win, sign me up."

The growth is obvious.

Tatum finished with 18 points on 6-for-22 shooting, including 1-for-7 on 3-pointers, but he also had a season-high 12 assists and nine rebounds.

"It wasn't like I had to do anything spectacular. It was just about finding the open guy," Tatum said.

That effort followed up his 16-point, 11-rebounds, five-assist performance in Game 1.

The Mavericks are applying defensive pressure on Tatum and often sending two guys to defend him. They don’t want Tatum to beat them one-on-one. The problem for the Mavs is that the Celtics have multiple scoring options (Jrue Holiday, Jaylen Brown, Derrick White, Kristaps Porzingis).

"They really test your discipline," Tatum said of defenses focused on limiting him. "Are you going to make the right play over and over and over again even if it's not resulting in you getting the shots or you scoring all the points?"

That mindset has allowed Tatum to remain an effective player in other areas. In his seventh NBA season, Tatum is playing in his seventh postseason. This is his second NBA Finals, and he has played in five Eastern Conference finals. The playoff experience is accruing, but a championship is missing from his résumé. The losses shape the player just as much as the victories.

Since Game 1, Tatum has answered pointed questions.

"Just over time, you learn how to deal with things," he said. "There was a point in my career where things did affect me or would bother me that, you know, to hear people talk about me on TV."

Asked about not being "the guy" in Game 2, Tatum responded: "It's not all about scoring. I can be the guy rebounding and getting assists and drawing attention, right? I'm going to have the ball in certain spots, right? I draw so much attention," he said. "I'm not always going to be the guy to get the shot, but sometimes sacrificing, being in those spots to make the play that we get the best shot possible, knowing that what they want to take away in their schemes.

"So being the guy in different ways. Maybe you don't score all the points, but you do all the things that put your guys in the best position to win."

Dallas coach Jason Kidd tried to play mind games with Tatum Saturday, calling Jaylen Brown Boston's best player. The Celtics ignored the comment, at least publicly.

Celtics coach Joe Mazzulla is annoyed at answering questions about Tatum’s shooting problems. "I'm really tired of hearing about one guy or this guy or that guy and everybody trying to make it out to be anything other than Celtic basketball. Everybody that stepped on that court today made winning plays on both ends of the floor. (That) is the most important thing.

"Jayson makes greatness look easy. He does it in a lot of different ways. He does it on defense, he does it on rebounding, he does it on passing, he does it on screening. He's a tremendous player and not hard to coach him. When he has the ability to affect the game in different ways, we're a different team. But it takes everybody to do it. That should answer everyone's question."

Of course, Mazzulla had more to say. "The emphasis and where he's grown over the last two years is to take what the defenses give him and learn to impact the game in many different ways. … Coming into a game, it's kind of similar to a puzzle and he's done a great job learning how to solve the puzzle and do different things."

The idea of how to win a championship and what it takes becomes more apparent to Tatum with each Finals victory.