The number was staggering. It hasn’t been talked about enough, Mike Brown said. And given the Knicks’ success at defending the paint during the regular season, it made what transpired in the second half of Game 2 — when the Hawks erupted for 42 points in the paint — even more stunning.

It was the worst half of Knicks paint defense all year by six points.

During the regular season, they allowed the third-fewest points in that area per game (43.4), and they had nine instances during the regular season when they only surrendered 42 points in the paint across the entire game. Monday’s lapse stemmed from a lack of execution, Brown said. From a lack of physicality, Josh Hart added.

The Knicks had a new weakness exposed, and starting with Game 3 on Thursday, Atlanta will almost certainly try to replicate that blueprint. It’ll fall on the Knicks, and all of their possible options, to figure out a response.

“I feel like we didn’t have that physicality that we did Game 1 and in the first half [of Game 2],” Hart said Wednesday in Tarrytown before the team flew to Atlanta. “I think that was the biggest thing. When you lose that physicality, then you allow them to kinda move at their own pace, kinda dictate their offense instead of you dictating it. Just gotta make sure we’re physical, have attention to detail and focus for a full 48.”

It could just be an anomaly. A one-off. The Knicks, in addition to being a strong unit at defending the paint and among the NBA’s best defenses over the final two-plus months of the regular season, were also the best fourth-quarter team in terms of net rating during the regular season. That made their collapse Monday an uncharacteristic one. But theoretically, Hart said, the Hawks will try to attack the paint again.

The simplest decision to combat the woes could involve playing Mitchell Robinson — the best Knicks interior defender — more, but that would come with inherent risks.

His minutes jumped from 14:30 to 18:09 in the opening two games of the series, but could Brown keep Robinson on the court more and risk a hack-a-Mitch strategy? And if he does give Robinson more time off the bench, whose minutes would dip?

These are the decisions and considerations that arise over the course of a seven-game series.

In the opening half of Game 2, the Knicks allowed just 16 points in the paint, but CJ McCollum, who shredded Jalen Brunson, finished with 16 points in the paint alone, including 10 in the second half.

Twelve of Jalen Johnson’s second-half points occurred in that area by the basket, too, and he set the tone with Atlanta’s first layup of the third quarter — pump-faking on the left wing after the Knicks went up 13, driving around Hart and finishing his shot before Karl-Anthony Towns’ help defense made an impact.

And when the fourth quarter arrived, that paint-scoring edge became especially noticeable, with the Hawks outscoring the Knicks 22-4. Jonathan Kuminga rolled off a screen and dunked to pull the Hawks within 93-85. He sent a lob pass over all the Knicks defenders to Onyeka Okongwu for another dunk on the next possession, too. Ball movement kept opening up lanes, and the Knicks kept failing to plug any gaps in time.

“You gotta give Atlanta credit,” Brown said. “We didn’t execute our defense the way that we could have. Or the way we should have, or the way that we have been doing throughout the first six quarters [of the series].”

Now comes the counter, though. Now comes Atlanta’s chance to turn this into a series-defining weakness. Now comes the chance for the Knicks to “keep the physicality going,” as Mikal Bridges said. To help in transition. To “show bodies.” To give a boost to whoever’s guarding the ball.

Now comes the playoff chess match.

“That’s why being focused and having attention to detail is so big in the playoffs,” Hart said, “because sometimes, it goes away from plays — and it just goes into schemes, it goes into personnel. You gotta be able to react on the fly. When you’re locked in, you have that attention to detail, you’re able to do that pretty seamlessly.”