The Celtics believe with every fiber of their being that they exist as a basketball team for one reason and one reason only — to choke the living daylights out of your offense. (Well, that and Ubuntu. But even their all-for-one, one-for-all philosophy springs forth from their collective appreciation of the black art of the NBA rotation).

There are many ways to measure defense in the NBA. The Celtics currently rank second in points allowed per game (behind Cleveland) and are first in opponent field goal percentage. That tells us something, but it doesn’t tell us nearly enough. The Cleveland Cavaliers of the mid 1990s proved you can hold teams scoring down by simply walking the ball up the floor and suffocating the shot clock.

Rebounding would seem to be a key indicator of good defense, but that too comes with caveats. Again, back in the 1990s, the New Jersey Nets were always among the league leaders in rebounding, simply because they missed a heck of a lot of shots.

The Celtics rank fifth in the NBA in total rebounds per game, which is good, but they rank first in rebounding differential. That means they get more rebounds per game than any other team in the league. Now we’re getting somewhere, but we can go even further. The Celtics also lead the NBA in something called Rebound Rate, which is the percentage of missed shots that they corral.

They rank second in defensive rebound rate (behind San Antonio) and are seventh in offensive rebound rate (San Antonio is dead last) so, while it’s safe to say the Celtics are the best rebounding team in the league, it’s also true that they protect the glass and attack it.

NBA statistics have come a long way since Harvey Pollack started charting numbers back in Philadelphia, but defense has always been tricky because there are so many dependant variables at play. Was a missed shot the result of some stellar one-on-one D, or because of a well-timed rotation from a big?

Does Marcus Camby get a lot of blocks because he’s a great shot-blocker (maybe) or because some of the teams he played on couldn’t guard a stump if it was dribbling a basketball (perhaps). Or maybe, Camby gets a lot of blocks because the specific defensive scheme calls for the action to be funneled to the middle where he and his Pterodactyl-like wingspan are waiting? See, it gets tricky.

The people who try to provide context for basketball statistics, be they sabermatricians, or “Stat Geeks” (in the loving words of True Hoop’s Henry Abbott), have given a lot back to the game in recent years, but they all agree that defense is, as ESPN’s John Hollinger puts it, “A black box.”

(There is one guy who disagrees. David Berri, the author of “The Wages of Wins,” who has a lot of interesting things to say about basketball, but that’s a whole other story for a whole other time).

The most important word in all this is “efficiency,” because buried within those 10 letters is a code that is somewhat difficult to crack but easy enough to understand. You hear coaches, and some players, talk about efficiency. You hear Hubie Brown talking about it all the time whenever he’s doing a game, even if he’s not using the word. You can go back even further and reference Frank McGuire and Dean Smith — who were true pioneers and flat-out stat geeks.

Simply put, efficiency measures how well you use your possessions when you have the ball, and how well you stop the other team from doing things when they have it. Because we like nice round numbers, efficiency is best described in terms of 100 possessions, and the Celtics defense is the best in the NBA with a defensive efficiency rate of 96.9.

1. Boston 96.9

2. Cleveland 97.5

3. Orlando 98.1

The reason why people believe Cleveland is a little better than the Celtics is because while Boston is a little bit better defensively, the Cavs are two points better offensively in terms of efficiency, but that’s going down a different road.

All those numbers are useful to understand what we’re seeing, but then, we’re not watching calculators. So let’s take a look at Kevin Garnett, universally hailed as the best defensive player on the best defensive team in the league.

The Celtics love to be able to play Garnett off players who aren’t known for their offense for two reasons. One, that obviously means there’s somebody on the floor who isn’t a particularly good offensive player, but two, because it allows Garnett to quarterback the defense and roam the paint like a free safety.

When called upon, though, Garnett is as good a one-on-one big man defender in the league. During their eight-game winning streak, Garnett had four matchups that required him to do different things. Two against Chris Bosh, whom he called one of, if not the best “fours” in the league, one against Shaquille O’Neal (because Kendrick Perkins was out with an injury) and one against Dirk Nowitzki.

In four games, those three players averaged 16.8 points and shot less than 39 percent. Even that’s a little misleading, because O’Neal managed to go 8-for-13 against a combination of Garnett and Big Baby Davis, but we’ll get back to Shaq.

Bosh, as Garnett alluded to, is one of the best offensive “fours” in the league. He’s quick and agile with a good jumper and he’s also left-handed, which can makes him a unique cover.

In the first matchup in Toronto, Garnett forced Bosh to take mostly jump shots and he constantly overplayed his left hand on the perimeter. The effect was an uncomfortable afternoon and a 5-for-16 shooting performance.

Back in Boston the next night, Bosh had a better shooting night, going 6-for-11, but Garnett essentially forced him to do the same things. Nine of his 11 shots were outside the paint, and the mere fact that he only took 11 shots in a game that went into overtime and saw the Raptors take 82 shots was proof that Garnett did his job.

Shaq

I wrote about this one after the fact, but what Garnett was able to do against O’Neal was use his quickness and footwork to stay in front of Shaq and keep him from having a direct path to the basket. In the first six minutes while the Celtics were setting the tempo offensively, Garnett was able to steal an entry pass and get a block while recovering on the weak side.

As Garnett said, you can’t really stop Shaq (actually, he said it was like trying to hold up a house with the walls falling down), but what he was able to do was minimize the damage which was important, considering the circumstances.

Dirk Nowitzki

Like Bosh, Nowitzki is a jump shooter. Unlike Bosh, Nowitzki takes a whopping 83 percent of his shots come from the outside, which is partly why people think he’s soft. But he is a very good jump shooter. In the first quarter Sunday, Nowitzki was 0-for-7 from the floor, and the Celtics got off to a 15-point lead. All but one of those shots came from outside the paint.

Against Garnett, few, if any, of those jump shots were of the clean variety and he had the second-worst shooting day of his season.

Each of those players brought different things to the table, but what stands out is how inefficient they were. Garnett essentially took each of those players and made them if not a non-factor then a non-decisive factor.

So, KG what do you think about the economic stimulus package? It starts with defense.

RELATED CONTENT

Truly invaluable links:

82games.com

Basketball-reference.com

The Wages of Wins

Basketball Prospectus

Knickerblogger.net

Paul Flannery is a regular contributor for WEEI.com. He can be reached at pflannery@weei.com.