New York Knicks head coach Tom Thibodeau, right, raises his arms after RJ Barrett made the winning basket during the second half of an NBA basketball game as Boston Celtics forward Jayson Tatum (0) walks off the court on Thursday, Jan. 6, 2022, in New York. Credit: Adam Hunger / AP

Ime Udoka said his postgame message was short. A repetitive result. Another gut-wrenching loss. Another huge blown lead. Another flop of a late-game performance.

There wasn’t much talk about the buzzer-beating 3-pointer to hand the Celtics a 108-105 loss to the Knicks on Thursday at Madison Square Garden. No, it was about “everything leading up to it.”

Those are the areas Udoka pinpointed after the game: The lack of mental toughness; the Celtics getting rattled whenever they’re not in a groove. It was a blunt assessment from Udoka. But reality is starting to get desperate: The Celtics dropped to 18-21 and in the lottery with the season nearly half-finished.

“It’s a lack of mental toughness to fight through those adverse times,” Udoka said. “It’s across the board. It’s a turnover here, a bad shot here, a missed defensive assignment here, and several missed rebounds tonight. So it’s a lot of different things. A calming presence to slow it down and get us what we want is really what you need at that point. And sometimes we all get caught up in it.”

It was the nature of defeat that felt so exhausting for the Celtics and their fans. Boston built a commanding 25-point lead over New York, looking like — similar to other losses this season — it was going to cruise to victory.

But the Knicks kept chipping away. The Celtics, to their credit, thwarted the initial comeback attempt. The Boston lead yo-yoed between comfortable and intriguing. But it wasn’t until the second half when the Knicks made their run — and delivered the Celtics another brutal blow.

Robert Williams III said postgame he agreed with his coach’s remark: “We get rattled a lot, especially when we face adversity.” That’s been clear for most of the season, and the Celtics don’t have an easy answer to fixing those issues. Udoka mentioned the C’s get rattled even when “it’s not the end of the world.”

“Either we’re going to make some adjustments and get tired of it or it’s going to keep happening,” Udoka said. “… We need some leadership. Somebody that can calm us down and not get rattled when everything starts to go a little south. I think it snowballs between our guys.”

The Celtics’ clutch issues appear to be never-ending, spanning different seasons and coaches. They looked like they took a step forward during a brief two-game win streak over the Suns and Magic. But the back-to-back losses to the Spurs and Knicks have thwarted any real momentum they had built.

That leaves a frustrated team and coach searching for answers. Williams said it’s on the five players on the court to pull together once the tide turns to the other side. And Williams said he’s staying positive: “There’s no doubt in my mind we can change it.”

“At the end of the day, there’s five of us out there,” Williams said. “The crowd was so loud that sometimes we couldn’t even hear coach. So I feel like with the players on the court we have to calm ourselves down, pull ourselves together. Like Coach said, we get rattled when we’re facing adversity. But it’s on us to look in the mirror and get that together.”

Story by Souichi Terada, masslive.com