CLEVELAND — It wasn't difficult to figure out exactly when the air swooshed out of Quicken Loans Arena.

The moment came after the Boston Celtics went on a 16-0 run during a 5:51 span in the second quarter.

With Paul Pierce awakened, Ray Allen popping his quick jumpers and Kevin Garnett hitting nothing but net on a turnaround jump shot with Rajon Rondo on the bench, a loss felt all but assured.

It was. The Celtics pounded the Cavaliers, 120-88, to give them their worst home playoff loss in franchise history and take a 3-2 lead in their best-of-seven Eastern Conference semifinal series.

For the second consecutive game, the Celtics schooled the Cavs in almost every aspect of the game, but once again certain numbers stood out.

The Celtics held the Cavs to 41 percent shooting and clobbered them 23-7 in second-chance points. "There was little that we did right during the course of the game," Cavs coach Mike Brown said. "We can't dismiss this game."

And the Celtics' Big Three — Pierce, Allen and Garnett — combined for 63 points on 25-of-38 shooting, doing the heavy lifting for the Celtics as a unit for the first time in the series.

Before Game 5, Pierce had been a missing piece in this particular puzzle. Not so Tuesday night.

The Celtics' forward found some of his game.

"Those guys were great tonight, all three of them, and Rondo did what he had to do in the second half," LeBron James said.

Allen led all scorers with 25 points. Pierce added 21, and Garnett had 18.

Shaquille O'Neal led the Cavs with 21 points and grabbed four rebounds. James added just 15 points on 3-of-14 shooting.

The Celtics didn't need Rondo to give the Cavs a hard time, and he didn't in the first half. But that's the only aspect of the game that anyone associated with the Cavs can look at positively.

The Cavs trailed just 50-44 at halftime, but that changed at the onset of the third quarter. Allen came out and made two consecutive 3-point shots to quickly double the lead to 12 points.

With Allen heating up, Brown sent guard Anthony Parker out on him and put Mo Williams back on Rondo. Rondo went directly at Williams to the tune of eight quick points before Brown called a timeout. After the timeout, Williams disappeared for the remainder of the third quarter, along with the Cavs' hopes for winning the game.

"We have to do a better job with our team defense," Brown said. "Mo had gotten beaten a couple times, but there were a couple of times when we didn't play the right defense behind him."

The blame is not solely on Williams; there's plenty to go around. After Tuesday's game, there has to be a question about James' health. After enduring a miserable Game 4, if he were true to form, he would return to inflict damage on the Celtics in Game 5. That wasn't the case.

James continued to play without his normal aggressiveness, a sure sign that something else is going on.

"I thought we did a good job of crowding him and contesting his shot," Garnett said.

He didn't score on a field goal for the entire first half. James didn't drive to the hoop, and most of his points came at the free-throw line.

"It is unlike him," Brown said. "He had an off night tonight, which is abnormal. He normally brings it for us each night. He'll be ready to go in Game 6," Brown said.

He'll need to be on Thursday night at the TD Garden, when the Cavs' season and possibly their future hang in the balance.