BOSTON — Marcus Morris sat at his locker stall running through all the moves that the Boston Celtics’ Eastern Conference rivals had made in advance of Thursday’s trade deadline. 

Tobias Harris to Philadelphia. Marc Gasol to Toronto. Nikola Mirotic to Milwaukee. 

Declared Morris: "The East is loaded up now."

Which begged the question: On a day in which the Celtics were largely observers — the team sending Jabari Bird and cash to Atlanta to open a roster spot but otherwise hoarding their assets for the long-anticipated Anthony Davis pursuit this summer — was Morris worried about a beefed-up East?

“Nah, I don’t do no worrying,” said Morris. "It is what it is. We’re still loaded, too, ourselves. So, s---, it’s going to definitely be a dogfight. It’s going to be fun. The competition is going to be fun. And I’m excited to see it.”

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The Celtics have been one of the top teams in the NBA for the better part of two months now, playing some inspired basketball ever since Morris and Marcus Smart elevated to starting roles following a seesaw start to the season. Still, Boston fell into some bad habits on Thursday night and allowed LeBron James and the Lakers to rally for a stunning 129-128 triumph at TD Garden behind Rajon Rondo’s first NBA buzzer-beater.

With the loss, Boston slipped back to fourth in the East. The wheeling-and-dealing Sixers and their new supercharged starting 5 with Harris lurk a half-game back with a head-to-head meeting next week in Philadelphia.

All of which to say is that every game matters now and the Celtics are going to have to work to earn a premium seeding. But if Boston players are any more nervous in the aftermath of their rivals’ moves, then they didn’t show it much on Thursday night.

"I'm going to be honest with you, you probably have to tell me who got traded,” said Kyrie Irving, who endured uncharacteristic shooting struggles throughout Thursday’s game and still almost won the thing for Boston in crunch time. "I haven't been on a lot of the wire about who got traded so I'll probably go home and look at it. I think Marc Gasol, right?”

Yup. And Harris. And Mirotic. Philadelphia made some depth move as well, all while moving former No. 1 pick Markelle Fultz to Orlando. The East became an arm’s race this week and Ainge had to essentially sit on his hands with the goal of preserving Boston’s top assets to chase Davis this summer when the team isn’t prohibited by the collective bargaining agreement.

After a reporter detailed all the moves for Irving, who was almost certainly playing coy about the East swap meet, he relented that Boston’s competition had improved.

"Those are great pickups,” said Irving. "I’m looking forward to going against those guys. Obviously, those are top contenders in the East so we'll see them down the line.  We have Philly coming up in the next week, in Philly, so that will be a great game. Just looking forward to the challenge of dialing in after the All-Star break and really focusing on the things that we want to do as a team and just get better at.”

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Morris caught the attention of social media Wednesday when he left a comment on a post about Philadelphia adding Harris. “Great pick up, not enough though,” Morris wrote on Instagram. He didn’t back down from the assertion, however, and admitted it was made a bit in jest.

“I know some people seen me comment on Instagram about the Tobias Harris tweet. Actually, Tobias is one of my good friends, so it was kind of like a joke,” said Morris. "But I think that was a great trade for them. They got a true professional, a guy that’s definitely going to help them out. And now, s---, it’s just amping the battle up even more.

“[Gasol is] a big pickup. I think [the Raptors] get a seasoned vet who has the opportunity to compete for a [championship]. So I think he’s probably very motivated, very excited. Mirotic to Milwaukee was a big pickup for them, too. I thought that was a power move by them. So it’s loaded up.”

The Celtics sounded like a team that didn’t anticipate any moves on Thursday. And they didn’t seem flustered by the loss in the aftermath.

"For us, we were pretty set,” Irving said of Boston’s lack of deadline maneuvering. “They made that very clear, our management. So I’m just happy that now we can just focus on the rest of the season and have some fun doing so. I’m just glad [the deadline is] past.”

Boston is confident that it has enough talent to compete in the East. The Celtics’ bench is starting to give the team a jolt more consistently, as emphasized Thursday when Jaylen Brown and Terry Rozier combined for 37 points and Daniel Theis had a career night with 20 points while keeping Boston close to the Lakers during the visitor’s third-quarter 3-point barrage.

It wasn’t enough on this night, in part because Boston’s defense was surprisingly lackluster as the Lakers shot 53.7 percent beyond the 3-point arc and set a new franchise record with 22 3-pointers.

Bad home losses to teams like the Knicks, Magic, Suns, and now the Lakers have put Boston in an unnecessary hole. This team might not be able to get up higher than No. 3 in the East, which would force them to play without home court in Rounds 2 and 3, should they make it that far.

Ultimately, the Celtics are banking on the talent in their locker room. They’re pinning their hopes on the notion that they haven’t played their best ball yet and will go to another level when the playoffs roll around.

But this isn’t the East we expected. The one that Boston was supposed to roll through after James went west. The path back to the Eastern Conference finals is filled with challenges and teams that are eager to prove themselves.

The Celtics’ hands were tied Thursday. They like the talent they’ve got and they weren’t going to dip into their future assets trade chest just for a marginal improvement. But the competition got better, the path to the NBA Finals is more daunting, and Boston can ill afford an early exit with uncertainty about Irving’s future (though it still seems a good bet he’s back in Boston, especially if the Celtics can land Davis). 

The deadline is gone but the work is just beginning for these Celtics.

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