At some point, one would expect the Celtics to take this kind of thing personally.

And by personally, we don’t mean individually.

You have to figure they’re tired of having sand kicked in their collective face, of having former players on television shaking their heads at the utter disappointment their season has been.

Sure, there are a number of teams that would be more than happy to be sitting here with a 38-26 record, but none of them were the overwhelming preseason favorite to represent the Eastern Conference in the NBA Finals.

And none of them were such willing victims of a home invasion as were the Celtics Sunday afternoon. It’s not like the Rockets need much help or prodding to produce the kind of worse-than-it-looks 115-104 beating they executed here, but still Celts’ complicity was unnerving.

The sight of James Harden rolling past flat-footed defenders for uncontested layups was enough to make the Garden gathering hoot on their heroes well before halftime.

Then, shortly after the break had concluded, Brad Stevens did pretty much the same in the avenue available to him.

Eric Gordon began the third quarter with a 3-pointer, and after Kyrie Irving missed a pull-up 18-footer, Gordon threw in another slightly longer trey. Stevens reached for a timeout.

Fifty-five seconds after he’d had most of 15 minutes to chastise his troops for the 65-33 deficit and offer sound advice, such as, “Maybe stand closer to the people in the red uniforms when they have the ball,” the coach was looking up at a 28-point deficit and wondering how to stop the bleeding.

But the patient wasn’t about to recover. Stevens knew it.

“The game was lost in the first 30 minutes,” he said later, “and, uh, that’s that.”

It still took a while for the Celts to find anything resembling coherence after that TO, but when Marcus Smart hit from beyond the arc with 1:26 to go in the third, it was an at least interesting, if not intriguing, 15-point game. But Harden got into the lane for a floater, and Chris Paul made two free throws. After the Celtics committed their second turnover in as many possessions, Paul tossed in a pull-up 3-pointer that was almost insulting in its casual nature.

The Rockets were fairly toying with the Celts, exiting the period the same way they entered it — with a 22-point lead. Only the usual leader’s ennui that accompanies such situations made this close. No question, the quintet of Terry Rozier, Jayson Tatum, Jaylen Brown, Gordon Hayward and Daniel Theis did a very good job revving the defense and harassing the Rockets into mistakes, but no one should mischaracterize this. Stevens certainly didn’t.

“You have to play well to have a chance to come back like that,” he said, “but it’s easier to be the team playing from behind than ahead.”

Like, nice of you to find the intensity gauge, but where was this kind of connected effort when it was truly needed, when you were getting Globetrottered on national television?

The defensive lapses that led to the easy Houston points were hard to take. The Celtics knew what they were up against here. Brown even laid it out to the Herald a day and a half before, saying, “If we’ve got the right attitude, I’m not even worried about it. If we’ve got the right attitude, we can beat anybody. If we’ve got a lazy attitude or an attitude like we don’t want to play, we’re going to lose. Simple.”

For the first half and a chunk of the third quarter, it was clearly the latter.

“Five guys have to play together exceptionally hard and on a string just to have a chance to get a stop against Houston, and that’s the same way against Golden State,” said Stevens, referencing the Celts’ next opponent. “You have to play exceptionally hard and together and on a string and leave no doubt on every possession just to have a chance to get a stop. That’s how good the players are in the league. So when we don’t have that, you’re not going to stop very many people.”

The coach was asked about tweaks to the rotation after this one, but if the Celtics keep performing in such a disconcerted manner, it might be a good idea for the team to issue those “Hello, my name is…” name-tags so they can introduce themselves to one another.

“We have to play better,” Stevens said. “Individually and collectively, we have to play better. As I’ve said many times, I have to coach better. We have to do better. And that’s harder, more precise, more together…”

The final slap across the kisser came with 50 seconds left and the Celtics holding only the smallest morsel of hope, down by nine points. Smart inbounded the ball from the frontcourt right sideline after a timeout, but Tatum did not come as aggressively as needed to the ball. Houston’s P.J. Tucker did, ripping off the rock to add a little ice to the caustic cocktail.

“We didn’t expect to be in this position, but it’s just one of those things that we need to work through it as a team,” said Al Horford, who made 7-of-8 shots on the way to 19 points. “It’s a commitment to winning and being consistent with it, and that’s been our biggest problem — consistency on defense and offense.”

Consistency, sure. But also the lack of fortitude to stand up in a timely manner to an opponent who’s pushing them around. At some point, you’d figure they’d have had enough of this.

But we haven’t reached that point yet.