It’s time to get off the fence and recognize what the Celtics are doing. If you’ve been following them all season, you’ve probably been expressing quiet optimism over their play since the All-Star break. If you wrote them off after a five-game losing streak that included two losses to the Pistons before the break, then it’s time to pay attention again. What the Celtics have done since Feb. 22 can no longer be considered a fluke or a hot stretch.

They’ve won 18 out of 25 games and taken control of the Atlantic Division with a defense that is dominating opponents at a historic rate, and in the last week and a half they have recorded dominating wins over the Heat, Sixers and Pacers. They added another notch in their belt with a 115-107 win at Miami on Tuesday who entered the game with the best home record in the league.

The Celtics are not the favorites in the East and despite their recent mastery of Miami, they would be a decided underdog in a seven-game series against the Heat. They still have a major matchup problem with the Bulls and after Tuesday it’s looking more and more likely that they would be on Chicago’s side of the bracket in the playoffs.

They may not be a true contender, but the Celtics are a legitimate threat again and have become more than just the team no one wants to play in the postseason. Their formula is simple. Play lock-down defense and spread the wealth offensively with Kevin Garnett and Paul Pierce taking the majority of the shots.

There was nothing conventional about the way the Celtics beat Miami on Tuesday, however. They shot 61 percent against one of the best defenses in the league and converted a rather absurd 16-of-27 shots from 16-23 feet and 9-of-14 from 3-point range.

It was a game that screams random fluke in a season that has been full of them, and there was nothing sustainable about the way the Celtics shot the ball. Their offense is still predicated on jump shots to an alarming degree and almost completely reliant on Rajon Rondo creating opportunities. But the real takeaway from Tuesday is how they kept responding to Miami’s patented runs.

“They just kept throwing punches at us,” Doc Rivers said after the game, and the Celtics kept answering.

They were down 5-0 in the first minute and led 13-9 at the first timeout. They trailed 20-17 midway through the first quarter, and led 33-22 at the end of it. In the second quarter, the unlikely reserve unit of Greg Stiemsma, Sasha Pavlovic and Ray Allen along with Avery Bradley and Garnett helped open up an 18-point lead.

The Heat kept coming back behind a superb game from LeBron James (36 points, seven rebounds and seven assists) and the Celtics kept holding them off. Pierce hit contested jump shots, Brandon Bass held his own in the paint and Rondo played the kind of coolly efficient game that has become so familiar lately with 18 points, 15 assists and just three turnovers.

The moment of truth came early in the fourth quarter when Chris Bosh pulled Miami within a single point. Rivers didn’t hesitate, bringing Rondo and Pierce back into the game after only two and a half minutes of rest. Bass made a jumper, Allen hit a 3 and then Garnett made four straight shots on four straight possessions.

“We’re not complicating the game right now,” Rivers said. “We’re keeping it simple.”

Rivers is employing an eight-man rotation that is really seven. Since moving to the bench, Allen has provided instant offense and a steadying presence to a reserve unit that needed both. Stiemsma has been a revelation and his seven rebounds went a long way in helping the Celtics control the boards in the first half.

The eighth player is Pavlovic, who has scored 20 points in the last three games on 7-for-10 shooting. The key, however, is Mickael Pietrus who continues to make progress from a severe concussion. If they can get Pietrus back then their defense becomes even more versatile and lately it’s been ferocious. 

Coming into Tuesday’s game, the Celtics had been allowing 89.1 points per 100 possessions during their last 10 games, a mark that as SI’s Zach Lowe pointed out, is better than 12 points below the league average. Included in those 10 games – which coincided with Bradley’s move into the starting lineup -- were five opponents who rank among the league’s top eight offenses. Defenses can get hot, just like shooters, but this has been an otherworldly stretch.

The Celtics put on an offensive show against the Heat, but it was their defense that pulled them across the finish line. Miami shot just 38 percent in the second half and the Heat were able to stay in the game in large part because they went to the free throw line 18 times and because they pulled down 11 offensive rebounds.

This is where the caution flags go up on the Celtics’ long-term chances. In addition to having the least effective offensive production of any of the playoff teams by far, they are also the worst rebounding team and routinely give up points at the free throw line. Despite these obvious issues – and they have not improved during the second half of the season – the Celtics keep winning games by decisive margins.

They have such a thin margin for error that they will have to be almost perfect to make a deep run in the postseason. Still, knowing what we know about this group, does anyone want to bet against them?