BOSTON — P.J. Tucker has not played a single minute for the Knicks this postseason. Since signing with them in March, he entered Wednesday’s Game 5 clash against the Celtics at TD Garden with 25 DNPs, appearing in just three regular-season games.

But he’s still made a major impact.

“He’s been great,” Jalen Brunson said Wednesday morning after Knicks shootaround. “The way he talks, the way he leads. Obviously, he’s been around the league a long time and he has a lot of experience and so when he talks, we listen. So having a guy like that on our team has been remarkable for us. He’s been fantastic since he’s been there.”

The Knicks have largely reversed the third-quarter woes that plagued them in the first round against the Pistons.

Entering Game 5, the Knicks owned a 17-point advantage in the third quarter and outscored the Celtics twice in the quarter in the first four games of the series. In the ones they didn’t, they were only outscored by one point and three points.

Against the Pistons, the Knicks were outscored by a combined 20 points in third quarters.

Brunson said the players get together and break down the game with each other at halftime before coach Tom Thibodeau gets in the locker room and begins talking to them. Tucker is a major part of that dynamic.

Their third-quarter performances have dramatically improved as a result.

“Obviously we want to play well throughout the entire game, but when we get to halftime, we try to adjust what we were doing incorrectly and we try to fix it,” Brunson said. “So we come out in the second half, you do it with a little more intensity, a little more communication, more focus. That’s it. You have to come back better. You have to realize what you’re doing wrong, realize what’s working, and come back.

“It’s a time to sit there, catch your breath and reflect and see where we can be better. We just take that time and we come out with more energy and see how we attack the game.”

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The 40-year-old Tucker, along with OG Anunoby, is one of only two players on the roster who has won a championship, which Tucker did with the Bucks in the 2020-21 season.

And Anunoby was injured for the Raptors’ championship run in 2018-19.

“Shout-out to P.J. Tucker for making sure we’re up and talking,” Josh Hart said after Game 4. “He brought that championship pedigree to us. He deserves a big shout-out. He’s just someone that always talks to us. He’s a champion and he’s bringing that mentality.”