BOSTON — During the height of the early season frustrations, Celtics coach Brad Stevens went a step beyond criticizing his team for poor shot selection, shoddy defensive rotations and repeated failures of execution.

The coach essentially said his players had gone soft.

"The game honors toughness," he declared following a Nov. 17 blowout home loss to the Utah Jazz.

It was a version of something that Marcus Smart had been saying both publicly and in the [...]

BOSTON — During the height of the early season frustrations, Celtics coach Brad Stevens went a step beyond criticizing his team for poor shot selection, shoddy defensive rotations and repeated failures of execution.

The coach essentially said his players had gone soft.

“The game honors toughness,” he declared following a Nov. 17 blowout home loss to the Utah Jazz.

It was a version of something that Marcus Smart had been saying both publicly and in the locker room ever since a lackluster preseason. At last, it appears everyone around him is starting to listen to the team’s most tenured player.

“I am constantly telling these guys that a lot of games that we’re going to win aren’t going to be pretty,” he said prior to Tuesday’s practice at Auerbach Center. “If you are trying to be pretty then this isn’t the game for you. You have to be able to get your nose bloodied and get dirty to win these games.”

Smart has not only talked the talk, he’s dirtied the floor since being inserted into the starting lineup three games ago in New Orleans, diving to the hardwood for steals and loose balls, and flashing an edge that was lacking during the team’s 10-10 start. It appears his persona in the starting five has started to wear off on his teammates as the Celtics carry a three-game win streak into Thursday night’s game against the New York Knicks at TD Garden.

“I think so,” he agreed. “Everybody is playing with a little more attitude — a little more swagger — which we were missing. I think we’re getting our swagger back.”

Smart said the winning ways have brightened the locker room and stopped players from “hanging their heads” around the practice facility.

“Just hanging their heads in the fact that they couldn’t understand what was going on either,” he clarified. “Everybody’s trying to find a way to come up with wins. While we were losing, we were all just upset. Not at each other, but just with the situation that we were handed.”

The situation has changed over the last three games — which the Celtics won by a combined 59 points — as the team has palpably shifted from trying to outskill and outshoot the competition each night to locking down defensively, attacking matchups and the basket more often, and playing with close to 48 minutes of focus.

“There were a lot of different reasons,” forward Jayson Tatum reflected of the slow start. “Maybe we believed the hype too much. We didn’t come out and perform. There was a big target on our back. Maybe we didn’t understand that fully.”

The hope is that the Celtics understand that they're moving forward with plenty of room to make up in the Eastern Conference standings. Boston entered Wednesday night tied with the Indiana Pacers for fifth place in the East — five games in the loss column behind the first-place Toronto Raptors.

“It’s funny because if you don’t humble yourself the world has a way of humbling it for you,” Smart asserted. “For us to go through what we’ve been going through, it was something that we needed. It brought us back to reality.”

With Jaylen Brown saying he expects to make his return Thursday night after testing his lower back bruise and spasms with a hard individual workout on Monday and a planned full practice on Tuesday, the Celtics could hit the court fully healthy for one of the first times all season as they look to avenge a dreadful loss to the lowly Knicks from Thanksgiving Eve.

They will do so with some of that swagger back, and some much needed blood and dirt replacing the pretty gleam from a summer full of fielding bouquets of hype. But they will also do so knowing a bit of that dirt comes from the hole they dug themselves through the first 20 games of the year.

“I go game to game,” Stevens said, “and I feel a little bit better about us week to week, but we still have a long way to go.”