Knicks guard RJ Barrett reacts in front of Hornets forward P.J....

Knicks guard RJ Barrett reacts in front of Hornets forward P.J. Washington during the second half of an NBA game Sunday at Madison Square Garden. Credit: AP/Adam Hunger

BOSTON — It was a simple question. And Jalen Brunson had an even simpler answer.

Asked after Sunday’s win what the biggest difference he has seen in RJ Barrett this season, Brunson started to talk about his confidence, then paused and said, “I think the biggest difference is that there isn’t a difference. He’s had the same mentality and approach to every game that I’ve been his teammate. It’s really that. He’s chipping away, hitting singles, hitting singles. He’s playing great.”

But it’s hard to find anyone outside of Brunson — and maybe Barrett — who dismisses that something has changed for Barrett. Through the first nine games of the season as the Knicks readied to face the Celtics Monday, Barrett has been their most consistent and arguably best player. And after summers and seasons filled with trade rumors, there is a sudden sense growing that maybe Barrett is a part of the building of the Knicks.

That has been reinforced in his absence — which came up Monday when he was scratched from the lineup, suffering from migraines. Before Monday, Barrett was averaging a team-high 22.6 points and not coincidentally the Knicks were 0-2 when he was forced to sit out with left knee soreness and that the team won three consecutive games when he returned.

In seven games, Barrett was shooting 50% from beyond the arc, 48.7% overall. And he has averaged 3.1 assists, a career-best. As he suddenly has seemed quietly confident there is the reminder that even with four seasons behind him in New York he is just 23 years old.

“I just think I have a little better rhythm and, of course, I think I’m growing as a player,” Barrett said. “It’s a system that I’ve been able to be in for a little bit. It’s kind of easy because I understand and know the reads, and so do my teammates, and we’re kind of all just working together right now.”

Knicks coach Tom Thibodeau was careful to put this in perspective — noting as he often does, this is a small sample size.

“RJ’s gotten off to a great start, and it’s just it is what it is: It’s a great start,” Thibodeau said. “One of the things I love about him is he’s 23 years old. He’s young. He’s going to keep getting better, building consistency is probably the biggest challenge. We’re seeing that now, but understand that there’s still a lot more to go into this and to improve upon, so I don’t want to put a ceiling on anything that he does. I think he can keep getting better and I think he will.”

Maybe Brunson is right then. For Barrett, the work has always been the thing, but the results were sometimes mixed. There have been reasons — like last season when he got off to a slow start after staying out of competitive play in the summer as he waited on a contract extension.

This summer, he was able to get on the court — extending last season with an impressive playoff performance and then playing a key role for Team Canada in the FIBA World Cup.

“[I’m] not in better shape,” Barrett said. “I think my summer was a little different. I played a little bit more basketball, as opposed to basically not playing at all last year.

“I got to play, make mistakes. Like in FIBA, when we played France, I was absolutely terrible. Played Brazil, I was horrible. I had four, five points, stuff like that. So, you kind of get to get some of those games out of the way. It’s easier.  . . . I think just my pace has been a lot better, knowing kind of when to go fast, when to slow down. I think that’s what’s helped me with my decision-making. Just trying to be better. It’s not college. You can’t go 100% speed the whole time.”

“I think there were times last year where he did it really well,” Thibodeau said of Barrett’s decision-making. “I think he’s getting a much better feel for things. He’s seeing different types of defenses. Sometimes he’s being blitzed. Sometimes people are going under. Some teams are switching. He’s starting to feel real comfortable attacking everything and he’s playing off people a lot better. He’s moving without the ball, he’s getting some easy buckets, and I think that goes a long way.”

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