Paul PierceFor the better part of the last month, the first few minutes of a given game were a fairly reliable predictor of how the Celtics would play that night.

A clunky start in Sacramento snowballed into an unsightly 22-point loss to the Kings. A 10-point deficit in the first quarter against the Clippers led to a 29-point drubbing. A 21-11 run off the jump presaged the Rockets running the Celtics off the court in Houston. It was a vicious cycle. The Celtics would start out poorly, particularly on offense, and as the game went on their ineffectual offense compounded with undisciplined defense, much to coach Doc Rivers‘ chagrin.

“Since we’ve been in this funk, Doc’s been saying throughout this tough ordeal that we have to continue to play defense,” Kevin Garnett said. “Our offense can’t dictate our defense.”

In the last two games, the Celtics may have finally grasped what Rivers has been preaching. For the second time in two days, the Celtics started off a game shooting poorly yet dug in to turn around their fortunes. On Friday against the Pacers they overcame 29-percent shooting in the first quarter and bounced back in the second quarter to assume a lead they would never relinquish. On Saturday in Atlanta, they went 16-for-41 from the field with nine turnovers to trail by 15 points after 24 minutes, yet surged back by holding the Hawks to nine points in the third quarter.

The resulting 89-81 win gave the Celtics their first win streak since Dec. 12 while giving Rivers another “blueprint” to show his team how to win a game even when their shots are not falling early.

Last month’s stretch, when the Celtics lost eight out of 10 and plummeted out of the still-early playoff picture, is not entirely forgotten just because the Celtics have won two in a row against viable contenders for spots in at least the Eastern Conference Semifinals. Still, the memory of that awful run is now tinged with the weathered effect of an Instagram filter, rather than in crisp high-definition.

Without putting too fine a point on it, the Celtics were really, really bad in the first half on Saturday. Their backcourt of Rajon Rondo and Avery Bradley, which was supposed to be re-energized by the return of the best perimeter defender in the NBA, watched Hawks two-guard Lou Williams go off for 21 points in his first 20 minutes of action. Point guard Jeff Teague was quieter, but still effective, in scoring 13 points and recording three steals in the first half. By halftime it seemed that Friday’s blowout win over the Pacers truly had been an outlier in a painful season.

The Hawks entered the funhouse in the third quarter, though. Down was up, up was down, Paul Pierce was hot and the Hawks, suddenly, were not. It took Atlanta more than five minutes of game time to finally record its first basket of the second half, on a 3-pointer by Kyle Korver. After Williams drained a three of his own 52 seconds later — his only basket of the entire second half — the Hawks did not make another field goal until Teague flicked in a runner more than a minute into the fourth quarter.

As is often the case in dominating defensive performances, the statistics only told part of the story for the Celtics in that third quarter. The Celtics would not have pushed back into the lead without holding Atlanta to 2-for-14 shooting while forcing seven turnovers and winning the rebounding battle 17-7, for sure. But Rondo diving between Williams’ legs to secure a steal and start a fast break was the defining snapshot of 12 minutes in which the Celtics did not just outplay the Hawks. They outworked them.

Even Jason Terry made an impact defensively, allowing Rivers to keep the still-recovering Bradley on the bench for the entire fourth quarter. By the time Rondo recorded his 10th rebound in the fourth quarter, his triple-double was just a punctuation mark on the Celtics’ second-half statement.

The Celtics were subdued in talking about their victory over the Pacers on Friday, stressing cautious optimism until they strung together a couple of wins to prove to themselves, more than anyone else, that they are capable of some level of consistency. After two wins in a row, both featuring sustained defensive resolve despite horrible starts offensively, they might finally be ready to believe. The rest of us will reserve judgment for now.

Next up, New York.

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