Paul Pierce has a great little saying that he has been using more and more in recent weeks: “I just try to give the game what it needs.”

When he needs to be, Pierce can still be a great scorer. When the game’s on the line, the Celtics want the ball in his hands (ask the Knicks). He can rebound when that’s what the game needs and he’s an underrated defender who plays his best on that end against the game’s great players.

But with Rajon Rondo out of the lineup, the Celtics are asking Pierce to be a facilitator, a point forward in other words, which is exactly what he was in a 99-88 win over the Pacers at TD Garden Sunday afternoon, which stretched the Celtics winning streak to 13 games.

Pierce had 18 points (on just eight shot attempts), 12 rebounds and 10 assists. It was his first triple double since March 8, 2006 against Philadelphia, which didn’t impress Pierce too much. “I’m just happy we got the win, truthfully,” Pierce said. “All those individual stats are good but it really doesn’t mean too much when you don’t win.”

About those numbers: Pierce is averaging 18 points, five rebounds and three assists, which is just about what he has put up since the big three era started. He has remained remarkably consistent during that time and his game has aged just as gracefully as he has.

“Paul discovered a long time ago the kind of player he wants to be,” said Pacers coach Jim O’Brien who was here when Pierce was beginning his ascent to superstar status. “He wanted to be one of the best in the world and he is. Nothing he does surprises me.”

Pierce’s coach for the last seven years, Doc Rivers, is similarly appreciative of his captain.

“He’s a great guy to have on your team because he does so many things,” Rivers said. “People just look at him as a scorer and his IQ, he’s a very smart basketball player. He’s the chameleon. We would rather have him in the scoring mode all the time. With this team, with the injuries we’ve had, he’s been a phenomenal utility player for us.”

No one has benefitted more from Pierce’s play than Nate Robinson, which is where we’ll start:

LETTING NATE BE NATE

Nate Robinson is not a point guard in the traditional sense and the Celtics have figured out that it would be a mistake to ask him to be one in the absence of Rajon Rondo.

“Nate’s not Rondo,” Rivers said. “We don’t want Nate to try and be a point guard. We just want him to just be a guard.”

What they want is for Robinson to create offense for himself, which is something he is very good at, and play pressure defense for as long as he is in the game. In 42 minutes, Robinson scored 18 points on 15 shots, made a couple of 3-pointers and was generally all over the court.

“I want him to stay Nate and be aggressive,” Rivers said. “That’s one of the reasons we’ve given the ball to Paul so he can stay aggressive and try to score.”

This is how it works. The Celtics start the game with Robinson handling the ball and running the offense. If the other team pressures him fullcourt, the Celtics give it to Pierce. If they try to pressure Pierce, it falls on Ray Allen to bring the ball up the court.

The Celtics had six turnovers in the first quarter and 18 in the game, which was one of the few things that kept them from blowing out the Pacers, while shooting 54 percent. So, Rivers left it to Pierce to run the offense.

“He helps Nate,” Rivers said. “He does what Delonte [West] was doing in some ways. Nate’s a good basketball player. He’s been terrific for us. He’s not a pure point guard. There’s thing that he can see and there’s things that he can’t see and you try to keep him out of those positions.”

There are a lot of things going right for the Celtics these days, but don’t underestimate the importance of the versatility that exists on the roster and Rivers’ ability and willingness to remain flexible. His genius as a coach is putting players in a position where their skills can flourish, and limiting the times when their weaknesses are exposed. There is no better example of that than in letting Nate be Nate.

SHAQ RETURNS

The alley-oop was a terrible idea. Preposterous, even. You want to throw an alley-oop to 38-year-old Shaquille O’Neal with a veteran big man like Jeff Foster, no shrinking violet either, protecting the basket?

“I think that alley-oop sent him back five years,” Rivers joked. “When Paul threw the pass, I thought there’s just no way. He not only caught it, he finished it.”

O’Neal finished the emphatic slam with a huff, breaking out what he called his “Diesel walk,” and hi-fiving the front row. When he completed the play with a free throw, he had 11 points in five minutes, which is all the points he would wind up scoring. They were more than enough.

“It’s great, just his presence alone,” Pierce said of the big man’s return after a four-game absence with various lower leg ailments. “I saw a couple of times where a guy had a wide-open shot in the lane and he missed it just because of Shaq being there. He sets the tone in there because we try to go to him early in the game to establish a post presence. It makes life easier for the guys on the perimeter.”

Shaq makes everyone’s life easier. Rivers pointed to his passing ability, which combined with Kevin Garnett’s is a lethal weapon inside. He’s also a force in the paint, as Pierce alluded to, and when he’s feeling frisky as he did Sunday, there’s still no one in the league that can stop him down low.

Shaq said that he was feeling good after the game and praised trainer Eddie Lacerte for helping me him mend. Rivers wanted him to be as close to 100 percent as possible before getting back on the court and he was not going to rush him back, even with injuries and attrition ripping away at the team’s frontcourt depth.

Even with all that, the Celtics can afford to be patient with Shaq. Jermaine O’Neal might be able to play Wednesday against Philadelphia if everything goes according to plan in practice on Tuesday. Shaq is very much a day-by-day proposition, and they’re fine with that.

“I’ll let you know Wednesday,” Rivers said. “With Shaq, the thing is when he’s healthy he plays.”

Shaq was feeling so good he even took a little jab at Pacers center Roy Hibbert, who had 17 points and 14 assists. Rivers gushed over Hibbert, but Shaq was unimpressed.

“I don’t. Should I? I don’t have any impression,” Shaq said. “The only one I have an impression of is Blake Griffin. Other than that I ain’t got nothing to say about nobody. Blake Griffin is the truth. All these other guys, I’m not impressed.”

THE INJURY SITUATION AND THE BENCH

Jermaine O’Neal is getting closer. Really. He went through practice on Saturday and if all goes well on Tuesday (the Celtics are off Monday), there’s a chance he’ll be able to play Wednesday.

Erden is battling a groin injury and a shoulder that hurts him more than he has let on. Rivers didn’t think he would be able to play against the Pacers, but he gave them seven minutes.

“Semih is not feeling well,” Rivers said before the game. “He is going to play but I don’t know how much he’s going to play. At this point [Saturday] we thought he wasn’t playing and then today he said he was fine. So we’ll see.”

Rajon Rondo said on Twitter Saturday night that he is out of the protective boot he’s been wearing, but there is no timetable for his return. Without any depth at center, or at guard, the Celtics are making do with what they have,

Glen Davis played 35 minutes, despite playing the game with a sore back. He had wraps and ice all over his body in the locker room after the game. Marquis Daniels logged 20 minutes, which helped keep Pierce and Allen’s minutes to a respectable level.

But Davis and Daniels are really all Rivers has right now on his bench. Avery Bradley and Von Wafer saw spot duty and it’s clear that neither have earned Rivers’ trust yet.

The coach used an all-reserve unit to start the second quarter and quickly subbed them out after they blew a 30-23 lead. Rivers was much happier with his bench in the second half.

“Our defense with the second unit in the second half, they couldn’t score but they got stops,” Rivers said. “In the first half they couldn’t score and they allowed the other team to score.”

Their 13-game winning streak is impressive, and all these wins in December will pay off when they start focusing on things like securing homecourt advantage in the second half of the season. They’ve been fortunate so far that even with all the injuries, Rivers hasn’t had to face a day of reckoning with Pierce, Garnett or Allen.

That day may come soon. There’s simply too much history and too much wear and tear to ignore the possibility. For now, they simply have to keep taking each day as it comes. That’s been their formulas this month and it’s paid off handsomely.