The Celtics beat the Nuggets Wednesday night, and you can make a convincing argument that this should not have been a surprise.

Denver, after all, is playing without Kenyon Martin, and the Nuggets are not a deep team beyond their top eight players. The Nuggets are also on the second game of a back-to-back after losing Tuesday in New York. On top of all that, they are also playing without their coach, George Karl, who is undergoing cancer treatment.

And yet, very few things that “should” happen for the Celtics this season have actually gone according to script. Their 113-99 victory at TD Garden (click here for the full recap) qualifies as their best home win since they beat a banged-up Portland in overtime back in January, which would make this the best home win of the season.

The Celtics did what they had to against the Nuggets. They pounded the glass and came up with 17 offensive rebounds. They also repeatedly ran high pick and rolls with their big men to take advantage of Denver’s lack of an interior presence and enjoyed a 58-28 advantage in points in the paint.

Five players scored in double figures. Rajon Rondo had a triple double with 11 points, 11 rebounds and 15 assists and Kevin Garnett had a double-double with 20 points and 10 rebounds. It was his first 20 and 10 game since Dec. 18 against Philly.

As we continue to look for signs of progress from the Celtics all of that tells us something. It tells us that they took advantage of mismatches and capitalized on them. That would be execution.

The Nuggets wound up slicing a 21-point lead to seven late in the third quarter. (Doc Rivers took the blame for that, saying he should have gone with a smaller lineup earlier to match up with Denver’s shooters). The Celtics still wound up winning by 14 points. That would be focus.

As the Celtics continue to make progress, here are three other things from a blowout win over a very good team at home.

PAUL PIERCE IS BACK

Rivers was asked before the game what stands out for him about Carmelo Anthony.

“His size,” Rivers said. “He’s the only guy that you look at and give the eye test and say that he’s much bigger than Paul [Pierce]. You don’t say that. Ever.”

Rivers threw in a caveat about LeBron James, rightly putting James in his own class in terms of size at the small forward position. Actually, Rivers said, “Put LeBron on an island,” which the coach would certainly like to do once the playoffs start and leave him there.

But his point remains. Anthony is one of the few players in the NBA who can match up physically with Pierce, who doesn’t get enough credit for being one of the strongest players at his position in the league.

It was certainly a test for Pierce and he responded with aggression. He had 14 points in the first quarter and he would have wound up with much more than the 27 he scored if he had not encountered foul trouble in the second quarter.

Pierce took 16 shots and only three of them were from beyond the 3-point arc. On everything else he was 10-for-13. He scored on drives to the basket and on the high-post isolation plays that are his specialty.

Anthony scored 32 points, but they were a hard 32. He took 23 shots and wound up going to the free throw line 16 times. Pierce made him work for it, in other words.

If it wasn’t clear yet, it is now. Pierce is finally healthy and playing his best basketball since the beginning part of the season. In their earlier meeting he scored just five points against Anthony and the Nuggets. That what his nadir before Rivers sat him down for three games.

“The Paul Pierce that you saw out in Denver wasn’t the Paul Pierce that usually shows up to play,” Paul Pierce said. “I’ve battled through a lot of injuries this year and right now I’m as healthy as I’ve been all year. This is our time to start playing well.”

THE RISE OF TONY ALLEN

Like a character in a horror movie, you just can’t kill Tony Allen. Every time he is left for dead he returns again, and usually with a surprise or two for those who would just as soon run him out of town.

Allen entered the game in the second quarter after Pierce picked up his third foul and he scored 10 points in just eight minutes of play. Included in that outburst was a vicious dunk off a no-look pass from Rajon Rondo and a nifty layup just before the halftime buzzer that showed not only great athleticism, but also a keen awareness of the clock.

Rivers stuck with Allen in the second half, leaving Marquis Daniels on the bench. He also used Allen in a very effective small lineup with Garnett playing center.

“I thought Tony, honestly, was the star of the game,” Rivers said. “I thought he turned the game around for us with his energy. With his defense.”

Since the acquisition of Michael Finley, Allen’s minutes have been squeezed almost dry. Yet Rivers praised Allen for continuing to work and not bemoaning his fate.

“Well, I just look at it like they got a quiet assassin and whenever they want to unleash him he’s going to be ready,” Allen said. “Ain’t no frustration over here because I know what I’m capable of doing.”

This has not been lost on his teammates.

“I really commend Tony because as a young player when you sit and you don’t play for a few games, it can bother you,” Pierce said. “Tonight was a night that we needed him. He stayed professional and when his number was called, he was ready. That’s what we need from everybody.”

Forget the 13 points, which were not totally insignificant. Allen’s main contribution to the Celtics last night, and possibly in the playoffs, is his ability to play defense against all manner of wing players. Against the Nuggets, that meant matching up with Anthony, J.R. Smith and even Chauncey Billups.

“Basically what I was trying to do was crowd their space and make them make passes,” Allen said. “Make the other guys beat us.”

Daniels has not played well recently — and make no mistake, Allen took his spot in the second half because he simply performed better.

“I didn’t think Marquis was playing great and I just thought we needed more energy,” Rivers said. “And guys are hungry. Scal’s hungry. Shelden’s hungry. Guys want to play and the guys ahead of them know that. That’s a good thing for this team. It really is.” 

Soon Rivers will have a decision to make and the guess here is that whatever he decides initially won’t be the final move he makes with his rotation. Daniels will play. Finley will play and yes, Tony Allen will play at some point in the playoffs.

Right now there are no wrong answers, just more solutions and that, as Rivers said, is a good thing indeed.

HOME-COURT ADVANTAGE?

The Celtics are 22-12 at TD Garden this season. If they had won, say, five more games that would give them a home record on par with Orlando’s and not coincidentally, would also put them ahead of the Magic for second place in the East.

Of all the strange things that have happened to the Celtics this season, their curious inability to win games at home is the most perplexing. This has been an issue even before the injuries and the boredom set in and no one seems to have a good reason for it.

There are 12 teams that have won more than 40 games in the NBA this season and the Celtics have won games against just two of them before Wednesday — Portland in January and Utah way back in early November. But now they have a chance to do something about it. Their win over the Nuggets started a six-games at home stretch against some of the best teams in the league.  

“We’ve been saying of late that e have to play better at home,” Pierce said. “We have been able to get the job done on the road, but this is where we eat. This is where we set our table. We have to do a better job here. We look forward [to this stretch] and we want to get all of these games.”

Playing well at home will be paramount in the playoffs because unless something drastic happens they will not have home-court advantage beyond the first round. (As an odd aside, it appears that the Celtics actually own the tiebreaker with the Hawks for third place if they finish with the same record as a division winner. In NBA logic, winning the Atlantic Division counts more than a four-game sweep).

Regardless of their regular season struggles, the postseason is a different beast entirely and it’s not as if the Garden is somehow an easy place for opposing teams to play. Asked if his home arena would be intimidating, Rivers replied, “It will be.”

He and his team are off to a good start as they try to make that a reality.