BOSTON -- For the Boston Celtics, three was indeed the magic number.

Their 3-point bombing earned them the No. 3 seed in the Eastern Conference. It enabled them to slip past the defending conference champion Philadelphia 76ers for three victories in the first round, and in the East semifinals, the Detroit Pistons were relegated to firing up wild threes by the Celtics' defense.

But against the New Jersey Nets, the Celtics ultimately could not count on the three -- or their ability to make one when they needed it most.

"If you're the Boston Celtics, with the team that we built, you've got to make threes," Celtics head coach Jim O'Brien said. "We just did not get that done."

By "we" O'Brien may as well have been talking about Paul Pierce and Antoine Walker.

No scoring tandem in the league stops and pops 3-pointers with such great regularity like Pierce, who averaged 2.6 3-pointers a game and shot 40.4 percent on threes in the regular season, and Walker, who sank 2.7 threes a game and shot 34.4 percent.

But in dropping three straight games to the Nets, the Celtics shot 25 percent or worse on 3-pointers in two of the defeats. Their worst effort of the series came in Friday night's 96-88 loss when Boston made only seven of its 30 3-point attempts.

"I thought it bothered them a lot," Nets coach Byron Scott said of the effectiveness of his team's zone D. "I thought it enabled us to get back into the game. Sometimes I got into it because I knew they have a nice little rhythm going, a nice little flow in their offense and I want to disrupt that."

And, as was the case late in the East finals, the Celtics had the hardest time shooting 3-pointers in the fourth quarter when the Nets would dare them to bust their 2-3 zone. Boston was a disastrous 1-for-13 on threes in the final quarter, Pierce making the lone trey with 11:10 to play when the action was just starting to get intense.

	“	We broke down and we weren't getting all back to try and make a run. We fell way short tonight by jumpers." ”
		— Erick Strickland

For the game, Pierce made two of seven 3-pointers in scoring 14 points, and Walker missed all but one of his nine attempts from three in adding 16 points.

"They were kind of in a box-and-one on Paul a little bit and that kind of took away our options," said Walker, who misfired on all five threes he took in the fourth. "That was a good call by them. But we got some good looks at the zone."

"They did a great job the last two games in the fourth quarter, executing and getting defensive stops," Pierce said.

With Pierce hounded by two defenders at all times and Walker unable to make even free throws (he missed a pair with 1:30 left and the Celtics trailing 89-86), Erick Strickland was put in the position to save Boston's season.

Strickland couldn't bail out the Celtics, despite sinking both of his threes in an eight-point first half. The reserve guard shot went 0-for-4 from three and 2-of-8 overall in the final quarter.

"We broke down and we weren't getting all back to try and make a run," Strickland said. "We fell way short tonight by jumpers."

"I think we penetrated most possessions well and against the zone, we wanted to drive to the middle and pass it out and try to hurt their zone with threes," O'Brien said. "They didn't fall."

As a result, the Celtics did.

Joe Lago is the NBA editor for ESPN.com.