The Celtics, the favorites to win the Eastern Conference this season, have hardly looked the part during their 1-2 start to this preseason. And the sloppy beginning was enough to irritate Stevens. He made no secret of it when his news conference began, either.

Celtics coach Brad Stevens took a bit longer than usual to begin his postgame news conference after the Celtics’ 102-95 preseason loss to the Cavaliers on Tuesday. Later, Marcus Smart said it was because he was busy sending a message in the locker room.

“I couldn’t be more unimpressed after our first three exhibition games,” he said.


Stevens said that his team’s defense has been “a sieve.” When he was asked what areas he would like to see improvement defensively, he replied: “Pretty much everything. I mean, we’ve got a lot of work to do. It’s pretty clear.”

It is worth pointing out that these are, in fact, exhibitions. Minutes have been limited, and All-Star point guard Kyrie Irving did not play at all Tuesday at TD Garden.

Nevertheless, it is also clear that Stevens would like to break bad habits before they become more concerning, and that there is some worry that the Celtics might believe some of the early hype that surrounds them.

“No shot do we dominate off talent alone,” Stevens said. “No team does that. You have to play together and play the right way.”

In the Celtics’ locker room later, the players mostly agreed with Stevens’s sentiment, but they did not seem overly concerned. The real season has not even started yet, and when it does, it will be long.

“I mean, let’s not overreact,” forward Jaylen Brown said. “I mean, it’s a fair assessment from Brad, but, at the same time, let’s not jump ship. Let’s just continue the course. It’s preseason.”


Marcus Smart hits the deck after he is fouled by Cleveland’s Jordon Clarkson during third quarter action at TD Garden on Tuesday. Matthew J. Lee/Globe staff

Smart, who was still scrapping for loose balls when he was on the court against third-stringers late in the third quarter, said this early hiccup was good for the Celtics, because it will humble them.

“We have to get back to being us,” Smart said. “We’re not doing things on the defensive end. We were being lazy. Guys were switching onto guys instead of guarding their own guy, and we want somebody to do the job for us and that’s just not us, and, rightfully so, Brad wasn’t happy, and he let it be known.”

The last time the Cavaliers came to TD Garden, they had LeBron James, and they left the arena after crushing the Celtics’ hopes in Game 7 of the Eastern Conference finals.

A lot has changed since then. Most notably, James does not play for the Cavaliers anymore. Cleveland is now expected to mostly crumble.

But the portion of Tuesday’s game that involved the Celtics’ regulars was quite messy for Boston. The Celtics missed all 12 of their first-half 3-point attempts, committed eight turnovers, and often let the Cavaliers slice to the basket without resistance.

“I don’t care if it’s preseason or not,” forward Marcus Morris said. “Everyone’s watching and expecting to see us playing well. As a unit, we need to.”

It did not help matters that the referee’s new focus on calling fouls on slight holds and grabs made the game mostly unsightly. The Celtics and Cavaliers combined to average 38.3 fouls per game last season, and they combined for 60 in this one.


Cleveland’s David Nwaba splits Celtics defenders P.J. Dozier (50) and Robert Williams (44) for a layup during the fourth quarter Tuesday. Matthew J. Lee/Globe staff

Boston trailed by 19 points at halftime, and when the second half began, all of the starters other than Terry Rozier were done for the night. The backups made a brief run, but never really threatened Cleveland’s lead.

Smart finished with 15 points and Morris added 14 to lead the Celtics.

Gordon Hayward had 7 points on 2 of 6 shooting, and it is obvious that he is still looking to regain his rhythm after missing last season with an ankle injury.

The Celtics will play their final game of the preseason Sunday, when they face the Cavaliers in Cleveland, and they are hoping to end this slate with something more positive.

“We’re not as good as advertised right now,” Stevens said. “At least we know that one week in.”

Adam Himmelsbach can be reached at adam. himmelsbach@globe.com. Follow him on Twitter @adamhimmelsbach.