The Celtics lost yet another entertaining game Friday night. They lost because they couldn’t make free throws, especially down the stretch. They lost because Aaron Brooks shredded their defense with his dribble penetration and shotmaking. And they lost because Luis Scola and Chase Budinger knocked down everything in sight.

It happens -- even to a team that prides itself on its defense and has now been shot out of its own gym during consecutive games. That’s a concern, no question, but the most perplexing thing about this 109-104 overtime loss to the Rockets (recap) was the mental breakdowns.

“We played like a high school team at times,” Celtics coach Doc Rivers said.

His team didn’t close out on shooters or box out well, which are both physical and mental mistakes. But they also didn’t get a shot off at the end of the third quarter. They didn’t defend the 3-point line -- at all. And one game after complaining about the refs, they were awarded 37 free throws and missed 13 of them, including three in the final 46 seconds that could have put the game away.

“There were so many little plays,” Rivers said. “No matter if you’re playing the Rockets, Cleveland, it doesn’t matter who you’re playing, [they were plays] you had to make. And [that] a veteran team should make. So that was a disappointment.”

The Rockets were without Kevin Martin and Trevor Ariza in addition to Shane Battier, Jared Jeffries and David Andersen, which made the outcome even tougher for the Celtics. Houston, after all, understood that it was backpedaling even before the opening tip.

“We knew we didn’t want to get embarrassed,” Rockets guard Kyle Lowry said.

Instead it was the Celtics who were left to explain another one that got away.

“You give a team confidence throughout the course of a game, especially a team that expects to lose, then they run with it,” Paul Pierce said. “Once it got late in the game they got real confident and it pulled them over the top.”

This homestand that started with so much promise has quickly been reduced to another lackluster footnote in a season that has had far too many of them.

Oh, and Rivers felt compelled to bench more than half the bench in the second half.

That and more in this edition of the Three-Pointer:

THE BENCH SHUFFLE CONTINUES

The obvious switch that Rivers made was replacing Marquis Daniels with Tony Allen. Again.

Daniels played a little over five minutes in the first half and was largely invisible. So when Ray Allen found himself buried in foul trouble (he fouled out in 16 minutes), Rivers called on Tony Allen, who scored 12 points to go with five rebounds and five steals.

“He deserved it,” Rivers said of T.A’s increased minutes. “In your business if you write crappy articles long enough, someone will replace you. Right now Tony is playing really well. He almost single-handedly got us back in the game with his energy.”

This is true. Trailing by four points when the fourth quarter began, the revamped second unit of Rajon Rondo, Allen, Michael Finley, Shelden Williams and Rasheed Wallace led a 15-4 run that gave the Celtics a seven-point lead.

Notice who was missing from that picture. Nate Robinson didn’t play in the second half and Williams replaced Glen Davis, who checked out with no points and one rebound in 11 minutes of action.

Before the game Rivers talked about the inherent struggle of trying to integrate Robinson into the lineup.

“With Nate, there are days when you want him to be a scorer,” Rivers said. “And there are days when you want him to run a team.”

The Celtics needed Robinson to run the team Friday night, but he wasn’t able to do so.

“I thought our starters had a great pace,” Rivers said. “They were phenomenal and I thought our bench in the second quarter hurt us. Hurt the rhythm, and that allowed them to get back in the game. And I thought it was as simple as that in some ways.”

Rivers did praise Finley, who he singled out for making heady, smart plays.

“We need more of that,” Rivers said.

The situation remains fluid. It’s likely that it will continue to sort itself out for as long as the Celtics play this season. The way things are going that may not be as long as they think.

IT’S TIME TO TURN RONDO LOOSE

Ray Allen wasn’t on the floor at the end of the game or in overtime and so when the Celtics needed a last-second shot there was only one option. Paul Pierce would get the ball at the top of the key and try to maneuver his way to his sweet spot for that pullback 20-foot jumper.

The Celtics have won a lot of games that way and Pierce had a strong game with 27 points, but without Allen to either serve as a decoy or a bailout option, everyone in the Garden knew where the ball was going and what Pierce was going to try to do with it.

The Rockets switched accordingly and as it happened, Rajon Rondo was left isolated on Chase Budinger. The rookie from Arizona was a revelation with 24 points, but the only way Rondo could have had a better matchup was if Yao Ming suddenly showed up with his broken foot.

It’s time to see what Rondo can do with the ball in his hands in these situations. All game long he broke down the Rockets. He shot 10-for-18 and scored 23 points to go with 10 assists (including one that allowed him to pass Bob Cousy for the franchise’s single-season record, which had stood for 50 seasons).

Rivers has resisted the urge to employ Rondo in such a manner. He’s a shaky free throw shooter and not a great, or even good, jump shooter. But he is the Celtics’ best weapon when he has the ball in his hands and he makes defenses react to him, which frankly doesn’t happen when they isolate Pierce.

The Pierce Iso-play is a mixed bag. He’s strong enough to get a shot off against almost anyone and he certainly has proved that he’s unafraid of the moment, but it will always be a contested shot.

Rondo has been the Celtics’ best player this season. You can argue all day and all night about who the team’s most important player is, or its most valuable player, but Rondo has been the best.

If they are going to do anything in the playoffs, Rondo will have to lead them. It’s time to see what he can do with the game on the line.

THE RETURN OF THE BEAST

It now appears that the knee tendinitis that bothered Kendrick Perkins had been a struggle for the last month or so. That would explain why Perkins tailed off so dramatically this winter from a player who was getting All-Star consideration to an overlooked fifth wheel.

“In this case he clearly [played] too long,” Rivers said. “Tendinitis is something that only the player knows.”

As is his custom, Perkins shook off that ready-made excuse and said he was fine. He’s tough like that, although like the rest of his teammates, perhaps some of that toughness should be replaced by making smarter decisions about his health.

He scored 15 points in 34 minutes and while the Rockets are a doughnut team -- no center -- these days, he was still matched up with Chuck Hayes, who is one of the league’s most rugged and physical low-post defenders.

Perkins pulled out a spin, drop-step reverse layup that was as gorgeous as it was stunning. While the Celtics can’t expect him to channel Hakeem Olajuwon on a regular basis, it would help their chances immensely if he could re-establish himself as a low-post presence.

If there was anything of a silver lining on a night that went horribly wrong, Perkins’ play was it.