AUBURN HILLS, Mich. -- Watching the Pistons try to score these days is pretty painful. After a fish-in-a-barrel performance in their opening-game victory over the Celtics, they have been reduced to a CBA, or even CYO, offensive unit.

In three straight losses, Detroit couldn't get to 80 points (or, as it's known in Dallas and Sacramento, halftime) nor shoot as high as 40 percent. The Celtics dismissed Game 1 as an aberration, promised things would be different the rest of the series and, so far, they have been right.

	Cliff Robinson and the Pistons have been held under 80 points for three straight games.

Watching the Celtics morph into a defensive team this season has been one of the many wonders in the NBA. It would have been hard to find a more porous, easy-to-score-against team this side of Golden State last year. In all the relevant statistical categories on defense, the Celtics were down near the bottom.

Now, they're at the top with, essentially, the same personnel. What did Jim O'Brien do? Lock them all in a room and force them to watch Kevin Costner movies until they promised to do better? No, he simply challenged them, imported a defensive coordinator and took advantage of the new rules to produce a team that has improved defensively all season.

This year, the Celtics were among the top five teams in the league in two important defensive categories: opponent's field-goal percentage and opponent's 3-point shooting percentage. They were 10th in points allowed. New assistant Dick Harter, who ran defenses for the likes of Chuck Daly, Pat Riley and Larry Bird, got them to buy into his schemes, and O'Brien got them all to buy into the 'defense-first' philosophy, something Rick Pitino tried and failed at.

Pitino, however, tried to do it by ranting, raving and pointing out mistakes. O'Brien does it with his trademark cool, collected demeanor and, when showing a tape of how to trap a pick-and-roll (one of Harter's favorite strategies), he shows someone doing it correctly. Little things tend to go a long way.

It helps, of course, that the Pistons have turned into stone throwers the past three games. The Celtics' defense is somewhat responsible for that, but there cannot be any sound explanation other than abject failure for an NBA team to score 64 points in a playoff game. The Celtics won that one only because they scored 66.

Naturally, both coaches termed that offensively challenged atrocity a defensive gem. That's the nature of NBA coaching today. Given their druthers, most coaches would prefer to win 66-64 than 125-119. The Kings and Mavericks had more points at halftime of their game the night before the Celtics and Pistons shattered -- and I mean shattered -- the post-shot clock record for fewest points in a playoff game. The previous low had been 142. They did a Tiger Woods 66-64--130.

"I would love to coach this high-powered, great fast-break basketball team where our guys can run all night and score 130 points and win the NBA championship with tremendous offensive output," O'Brien said. "But we built this, or attempted to build this, from Day 1 for the long term and we started at the defensive end."

And those wild and crazy, high-octane Mavericks are now home for the holidays while the Celtics play on, a victory away from reaching the Eastern Conference finals.

The arrival of Harter was a master stroke. He had been unemployed last season following the Pacers' coaching Diaspora, which saw Bird go back to Florida and Rick Carlisle to the sidelines before landing the Detroit job. But you still have to play defense as opposed to talking about playing defense, which had been the Celtics' preference until this year.

The legalization of the zone defense was a big boon for the Celtics because, basically, they don't have a lot of strong, one-on-one defenders. They would routinely get bullied and overpowered inside in previous years due to their lack of interior size. They had no real intimidator back there -- they still don't -- but the rules allowed them to use floaters and cover men to help out players such as Tony Battie. (If they ever get to play the Lakers in the Finals -- can you believe we're saying that? -- you watch what they do to Shaquille O'Neal. You won't be able to even see him in a halfcourt set.)

	“	I would love to coach this high-powered, great fast-break basketball team where our guys can run all night and score 130 points and win the NBA championship with tremendous offensive output. But we built this, or attempted to build this, from Day 1 for the long term and we started at the defensive end. ”
		— Jim O'Brien, Celtics coach

They continually front the post, which a lot of teams do. But the rotations now are quick and crisp and, should the entry pass succeed, the ball handler will immediately find someone in his way. They trap the pick-and-roll to the point where the trap man can sometimes be seen staying with the ball handler all the way to halfcourt. O'Brien said his players were tired of losing, eager to win, and willing to do almost anything to change things. He told them: Start defending and you'll be amazed at what you see.

In the playoffs, opponents are shooting 40.2 percent against the Celtics, the second-lowest figure among the still-surviving teams (the Lakers are first at 38.8) Only four surviving teams have a better defensive field-goal percentage for 3-pointers. Only the Pistons have allowed fewer points. You want to slog it out with the Celtics? Do so at your own peril.

"To me, tempo in this series was never an issue," O'Brien said. "I never thought, 'Gee, we need to establish a different tempo.' This tempo is fine with us."

Now, the Celtics talk like they're a defensive juggernaut, which, against the Pistons, they have been. Frankly, there isn't going to be a lot of difference should they meet the Nets in the conference finals. Who can shoot for New Jersey? Kenyon Martin? Jason Kidd? Keith Van Horn? The Celtics, like many teams, can be exposed when the other teams fast break, and that might be Jersey's best hope because few push it up the floor like Kidd.

But we're getting ahead of ourselves here. The Celtics still haven't finished off the Pistons, although the consensus now is not if they'll do it, but when they'll do it. Maybe Jerry Stackhouse will finally have a breakout game; would you say he's overdue? Maybe the Pistons will discover how to shoot the ball and some of their role players (Chucky Atkins, Jon Barry) will actually do something to help the cause. But you have to think that the past three games have been an accurate indicator rather than the first one. And, when you're facing elimination, those rims start looking like golf holes in the fourth quarter of a close game.

If the Pistons looked clueless on offense when they still had wiggle room, well, you can imagine how they might look when the choices are 'make shots or make putts.' They could force a sixth game; that would not be a shocker. But with defense generally ruling in the playoffs, the Celtics have shown themselves more than up to the task. You would have been institutionalized to have made such a suggestion a year ago.

Peter May, who covers the NBA for the Boston Globe, is a regular contributor to ESPN.com.