Even with Kevin Garnett back in the lineup, the Celtics have been flirting with disaster. With Garnett back, they narrowly escaped against a short-handed Portland team and the mediocre Clippers.

But wins are wins in the NBA, and after a while they offer a coating of respectability after the details have been forgotten. The reality is that Garnett can’t solve all of the Celtics' problems. He can’t reverse their inability to secure defensive rebounds. He can’t stop the C's from turning the ball over 16 times a night, and more than anything he can’t force them to keep their collective focus no matter how intense he is on the court.

On Thursday night the Celtics played the Magic, and all those problems came flooding back after they blew a 16-point second-half lead in a disastrous 96-94 loss.

The Celtics lost after Rashard Lewis drove around Garnett on a busted play, while Rasheed Wallace’s weakside help was two steps too late. They lost after J.J. Redick made an improbable 3-pointer to tie the game seconds earlier, a play that had Doc Rivers fuming about the team’s execution.

True, they lost after the Magic took 40 free throws to the Celtics' 18, and they lost after two Eddie House 3-pointers were changed to 2’s. After all that, the Celtics still had a chance to come away with the victory, but Wallace’s 3-pointer at the buzzer sailed wide of the basket.

“We deserved [the loss],” Rivers told reporters in Orlando. “An 11-point lead at halftime I told them was a joke. We should have been up by 20.”

Rivers continued: “Our focus kept going in and out.”

So now the Celtics have dropped the first game of this all-important three-game stretch. They play the Hawks Friday night in the second game of the back-to-back — a team they have not beaten all season — and the Lakers on Sunday.

Losing all three is a distinct possibility, and what stings is this was a game they could have won. A game they should have won. It won’t get any easier from here, and no one should have any illusions about Garnett’s ability to cure everything that ails them.

Here are the other three things we learned last night:

THE GOOD, THE BAD, THE SHEED

On the one hand, Rasheed Wallace plays his best basketball against the Magic. Few people can frustrate Dwight Howard like Wallace can, with his ability to overplay the passing lanes and throw the big man’s timing off.

Wallace also had the hot hand shooting the ball from deep, finishing with 17 points. It was one of Wallace’s best games in weeks.

But when the Celtics needed Wallace to close weakside against Lewis, he was nowhere to be found. It wasn’t the only time the Magic took advantage of Wallace’s slow reaction times, either.

Wallace has remained a maddening enigma on the court. He's prone to getting technical fouls — he got another one after yelling, “And one,” after a made basket — and launching too many 3-pointers, while at the same time dominating on the block whenever he chooses to go down low. This is nothing new, of course, and right now thousands of Pistons fans are nodding their heads in unison and saying, “We told you.”

The final sequence was uniquely emblematic of the Celtics and Wallace’s play last night. After the Celtics trapped Redick 40 feet from the basket and denied Vince Carter the ball, Lewis only was able to get it under duress as a last option. But as Lewis turned the corner on Garnett, and turned it with ease, there was no one waiting under the basket. It was as wide open as Redick had been on his game-tying 3-pointer moments earlier.

The Celtics played great defense for half the time and were nowhere to be found when it counted the most.

It’s not fair to blame last night’s loss on Wallace. He did, after all, play very well up until the final minute, but if ever there was one play that encapsulates where the Celtics are right now it was that one — with Garnett getting beat and Wallace nowhere in the picture.

DON’T BURY RAY ALLEN JUST YET

True to form, Ray Allen re-awoke against the team that gave him so much trouble in the playoffs last season. In his previous five games Allen had failed to reach double figures three times and had shot better than 50 percent just once (against Dallas).

But against the Magic, Allen came out blazing, making his first seven shots and finishing with 20 points while making 8-of-12 shots and going 4-for-8 from 3-point range. It was a vintage Allen performance right up until his final shot, when he rushed a 3-pointer with 10 seconds left on the shot clock and the score tied at 94-94.

If you’re an optimist, Allen’s performance was a good omen. The Magic have played him tough, and he helped corral Carter into a dreadful 2-for-13 performance.

If you’re a pessimist, you want to see him do it again and again over the next few games before you’re ready to concede that Allen has gotten his groove back.

The reality of the situation is that the Celtics need Allen to be the player he has been during his career. They rank in the middle half of the NBA in 3-point shooting, despite Pierce’s career-best shooting this season. Allen’s counterpart on the bench, Eddie House, also has had a subpar shooting season, but House doesn’t have nearly the track record that Allen does, nor the responsibilities.

If the Celtics are going to remain among the elite, their shooting is going to have to carry them offensively. They are a woeful offensive rebounding team and they continue to be too careless with the ball. Only by shooting a high percentage can they mask those deficiencies, and Allen has to be the one who takes the lead.

STAN VAN GUNDY GOES FOR CHECKMATE?

Van Gundy takes a lot of heat for his personality, and most of it is self-inflicted. He has been known to complain about, well, everything. He complains that his team doesn’t get enough respect from the league. He complains about his own team so much that his players have asked him to cool it.

But don’t let anyone tell you that the man can’t coach.

With his team flailing away, Van Gundy inserted Marcin Gortat into the game alongside Howard and moved Lewis to the 3-spot. The super-sized lineup gave the Celtics all kinds of matchup problems, especially with Kendrick Perkins on the bench in foul trouble.

Howard and Gortat were too big for Wallace, Garnett and Glen Davis to handle, and Lewis made life miserable for Pierce on both ends of the floor.

The Celtics have had uncommon success against Howard and the Magic by playing Perkins straight-up against the big man, something very few teams in the NBA are able to do. This effectively negates Orlando’s biggest advantage, which is having Howard pass out of double teams for open 3-pointers.

Rivers said something interesting to the press after the game, noting that the Celtics don’t care if Howard gets 40 points because that means the rest of the Magic aren’t shooting 3’s. But by utilizing the twin towers look, Van Gundy reasserted the strategic advantage and forced the Celtics to match up with not one but two 7-footers, while having the freakishly long Lewis tower over Pierce.

Expect to see that lineup again if these teams meet in the playoffs, and give Van Gundy credit for making the best move of the night.