A week ago after a nationally televised loss, the Celtics stood up after their latest fourth-quarter collapse against an elite team and accepted collective responsibility for their breakdown.

They would get better, they said. Their focus and execution would improve and the breakdowns, both physical and mental, would stop. At least, it sounded convincing.   

A week later they seemed on the verge of regaining the benefit of the doubt after ripping off three straight wins, even though the opposition could only charitably be described as mediocre.

The true test would come with yet another nationally televised showdown, this time against the Magic, and once again they failed.

“You know, one of the guys said, ‘We’re better than Orlando,’ ” Doc Rivers said after the latest excruciating meltdown resulted in a 96-89 loss to the Magic. “And I said, ‘No, you’re not.’ That’s a bunch of crap. They beat you three games. Two at your place. They’re better. They knocked you out of the playoffs last year. Orlando’s better than us right now. Atlanta’s better than us right now. LA’s better than us right now.”

True. Rivers went on to say that all that doesn’t mean that the Celtics can’t recover and be the team everyone in the locker room evidently still thinks they are, but this is the reality.

The Celtics are 1-8 against Orlando, Atlanta and the Lakers. Their win over Cleveland came back in October and doesn’t matter much in the grand scheme of things right now. They have defeated exactly two teams at the Garden who have won more than 30 games — Utah and Portland — and both of those came with major extenuating circumstances attached.

With one game left before the All-Star break, the Celtics are more pretender than contender. That’s who they are and it’s past time they recognized that if they want to alter that reality.

Here are our three things from a wasted Sunday at the Garden:

ANATOMY OF A COLLAPSE

The Celtics are beginning to earn an ignominious reputation as a team that falls apart in the second half. It’s a reputation they have more than earned over the last month and a half. “We have a whole work of art right now,” is how Rivers put it.

They have had defensive breakdowns and offensive slowdowns. They have played in spurts, and then not played at all. At times it’s been a lack of production from the bench, at others it’s been the starters. This latest collapse, though, stands out for being so thoroughly definitive.

After playing one of their best halves of the season, the Celtics simply collapsed and it was on everyone. From the time Rajon Rondo knocked down a 3-pointer with 7:16 left in the third quarter to the moment Tony Allen mercifully made a pair of free throws at the 1:33 mark, they were outscored 19-0.

They turned it over five times during that stretch and allowed the Magic to make four 3-pointers; the one thing they absolutely do not want to surrender against Orlando. When the third quarter was over, the scoreboard had been tilted 25 points in the Magic’s favor and a day that could have served as a springboard for bigger and better things, became just another chance to vent.

“We were making up our own coverages, defensively, switching,” Rivers said. “We gave up nine points on switches that we never switch.”

Then Rivers said what might serve as the team epitaph if they can’t get their act together: “I love our team,” he said. “But we tend to be front runners.”

There can be no more damning statement for this team then that one. The front-running charge is one they fought during the championship run in the playoffs and it stayed with them last season after their 29-2 start. Here we are in the winter of 2010 and it still haunts them.

“There’s no excuses for that,” Kevin Garnett said and he’s right. “There’s no answers for that and we just got to lock in. For some reason, third quarters have been kicking our behinds this year. We just got to get better at it. Period.”

In fairness to Garnett and the rest of the Celtics, what else could they say? If they had the answer they would fix it. If they knew the problem they would address it.

The coach and the players continue to talk about execution and attention to detail, but at some point, perhaps these things can’t be fixed. The burden is on them to prove otherwise.

THE DWIGHT HOWARD RULES

Few teams, if any, defend Dwight Howard better than the Celtics. Whether it’s the brawn of Kendrick Perkins or the smarts and experience of Rasheed Wallace, the Celtics master plan for defending the Magic rests in their ability to play Howard one-on-one.

In fact, the Celtics have said they don’t care if Howard scores 40 points against them because that means that the Magic’s perimeter shooters aren’t launching 3-pointers. The Celtics are never happier then when Howard is demanding the ball in the low-post and trying to get the Orlando offense to run through him.

Their gameplan was executed perfectly in the first half. On offense they drove to the basket and forced him to pick up two quick fouls and they certainly weren’t complaining when the ball stopped on the block on the other end.

When a frustrated Howard picked up his third foul early in the second quarter by elbowing Wallace away from the ball, it was almost letter perfect. Howard’s first half line read two points and three rebounds in eight minutes. Perhaps more importantly, the Celtics held the Magic to 4-for-11 shooting from 3-point range.

But in the third quarter everything changed as Howard came alive with nine points and seven rebounds. True, the main damage was done from behind the arc as Vince Carter and Rashard Lewis began bombing away from long range, but give Howard credit too. His looming defensive presence played a major part in the Celtics breakdown offensively.

There is nothing wrong with the Celtics plan against Howard and the Magic. Indeed it has proven successful more times than not in the past. But when they fail to stop him and allow the Magic shooters to fire away at will, the result is something like a quarter in which they get outscored 36-11.

MARQUIS DANIELS SURPRISES

Rivers, honestly, didn’t think he would get all that much from Marquis Daniels Sunday based on the way he played in practice on Saturday.

“Marquis played phenomenal,” Rivers said. “I’ve got to tell you, I was shocked by that.”

Daniels logged a shade over 12 minutes and scored eight points to go with three rebounds. Welcome numbers all, especially since Daniels did most of his damage in the paint. It will take Daniels a few games to get back into rhythm and one shouldn’t expect him to score at that rate consistently.

But Daniels’ presence allowed for a significant change in the first half when Rivers rolled out a lineup to start the second quarter that didn’t have a single player from the starting five on the floor.

Eddie House, Tony Allen, Daniels, Glen Davis and Wallace may be one of the quirkiest lineups any team can run out on the court.

There isn’t a “true” anything to be had with that fivesome. There’s no real point guard. The wings aren’t exactly 2’s and they’re not really 3’s. The power forward is undersized and the center has had a long career by not being a true pivot man. All five survive because of their specific skill sets and ability to blend with different combinations.

While we may not see the bench deployed en masse as a general rule of thumb, having a 10-deep rotation could play substantial dividends over the final 31 games of the season, specifically in that it would allow Rivers to rest Paul Pierce and Ray Allen significantly more then he has this season.

Allen in particular has played too many minutes this season. He even suggested a few weeks ago that it wouldn’t bother him in the slightest if Tony Allen and Daniels played more minutes over the second half of the season.

That’s something that needs to happen soon (assuming, of course that the Celtics don’t make any substantial changes to their roster). After a hot start Allen looked slow in the second half and once again checked in with a substantial 39 minutes of time.

But the Celtics finally have their full complement of players, and if nothing else it eliminates the injuries as an excuse for not playing well.