During a 3-4 stretch that followed, some questioned the club's age and its ability to hang with younger, more athletic teams. The one piece never called into question was the performance of Paul Pierce, and in two wins since the slump, he is the one making all the noise.
After Wednesday's otherworldly performance in which he had 27 points, six assists, six rebounds and no turnovers in 43 minutes against Philadelphia, observers are wondering what's next.
"He's guarding guys, he's rebounding, he's making big shots, he's taking charges," said Celtics head coach Doc Rivers. "I mean, I don't know what else. He can cook tomorrow's Thanksgiving dinner for someone and then he'll be doing it all. He's been terrific."
Indeed, Pierce's solid play has been the one constant in a Jekyll-and-Hyde season that has seen wildly inconsistent play on several fronts for the C's.
There was the double-double and lockdown defense in the opener against Cleveland, the 20-point third quarter in a win over Chicago and 27 points on 10-of-14 shooting against New Orleans.
In a victory over Utah, Pierce was held to 13 points but dictated much of the action, recording six assists, six rebounds and three steals in limited minutes. His 24 points stood as the lone bright spot in a loss to Atlanta two nights later.
Then, as Kevin Garnett began to limp, Ray Allen continued to miss and Rajon Rondo found himself an observer late in games, Pierce took his game to a new level.
His 33-point effort in Sunday's overtime win in New York was punctuated by an assist to Garnett on the game-winning basket. Pierce made 6 of 7 3-pointers in that one and is now making nearly half of his attempts from beyond from the arc.
Essentially, while several Celtics search for their game, Pierce is locked in.
He may even lead the league in humility.
"I'm just doing the things I know that I can do and just try to do them within our system," Pierce said.
That system also involves intelligence on the defensive end, a trademark of the current Celtics. Pierce, again, provided the best example of that against Philly, when he took a charge on Andre Iguodala with 34 seconds left and Boston clinging to a two-point lead.
"It's what we talk about," Pierce said. "I mean, if the charge is there, the coach wants us to step up and take the charge. That's pretty much the only thing I could've done in that situation. It was like Iguodala coming at you full speed. He's so athletic that once he gets in the air, I'm not going to block his shot. So I just try to stand there and take the charge."
That play came amid a stretch of 26 minutes, 43 seconds without a breather for Pierce. His only time on the bench came in the first 5:57 of the second quarter.
As Garnett put it after the game, "Tonight was all P. Pierce."
"He's the Truth, man," Garnett continued. "He took charges. When we needed a bucket, he got buckets. He got me easy shots. He got [Eddie] House easy shots. … When your captain's going like that and your team leader's going like that, in the flow — you know, he gave everybody insurance."
In addition to everything else, Pierce has been giving his club an earful when it needs it. Garnett said Pierce's halftime talk was a catalyst in Boston's win over Golden State last week, and Pierce was at it again on Wednesday.
According to Rivers, Pierce began to get on his teammates during a second quarter that saw the Sixers score 29 points. He then gave it to the C's at halftime.
Pierce's totals after the rant: 15 points, four rebounds, four assists and the charge that saved the game.
"At the end of the day, it was all Truth and his impact on the game," Garnett said.
It has been since the season started.