Here were the Celtics cruising right along with a nice little lead and Rajon Rondo making like a cross between Earl Monroe and Clyde Frazier.

They were aggressive on defense and shooting the lights out on offense. The Cavaliers? Just the opposite. No ball movement, no defensive presence, no energy, no nothing.

And then Glen Davis swatted down hard on his one-time mentor Shaquille O’Neal, and the Big Fella removed himself from the game and lumbered back to the locker room. The cause was a “significant” thumb injury, and whether it was a coincidence or not, everything suddenly changed.

Without Shaq, the Cavs became smaller, but not that much smaller, and they became much, much faster. They also made shots all over the floor and in turn, the Celtics simply did not.

There were reasons for all that, of course. Better rotations from Cleveland, less movement from Boston, fewer fast breaks opportunities on account of all those Cavaliers makes.

The final score was 108-88, but the game played itself out in the second half when the Cavs outscored the Celtics by the fairly stunning count of 60-32.

“I know you guys are tired of writing it in your columns,” Kevin Garnett said of the team’s second-half woes. “I apologize for all that. At some point there has to be action. You’re right. You’re totally right. Doc [Rivers] has a saying, ‘You have to run through the whole race,’ and we’ve got to do that. Until we players decide to do that, we’re going to be in this predicament.”

With that, let’s get to our three things:

AS RONDO GOES …

The Celtics scored 21 points in the first seven minutes of the game and Rajon Rondo had a hand in all of them, either by scoring them himself or dishing off for assists.

Rather remarkably, Rondo played 38 of the next 41 minutes and added just seven more points and assists to his totals. The two things might be related.

Rivers acknowledged that he should have rested Rondo earlier in the game, but he kept him out there for all but a few seconds until he removed everyone with about three minutes remaining.

Beyond that though, the Cavs made a concerted effort to keep Rondo out of the paint. Without Paul Pierce in the lineup, Rondo is the only Celtic who can create offense for himself and others. That fact is not lost on the opposition.

“When you scout for Boston there’s certain guys that make that board before the game,” LeBron James said. “Those type of guys you have to stop, and he’s one of those guys. First couple of years here in Boston he wasn’t on that board. He was just a fast point guard and you had to get back, but other than that you didn’t talk much about Rondo.

“Last year he made a name for himself. Now he makes that board and you say, OK, this is what we have to do against Paul [Pierce]. This is what we have to do against Ray [Allen]. This is what we do against KG and this is what we do against Rondo. When you make that board, you are definitely a good player.”

So, King James has sanctified the newest knight of the realm. Rondo is a target and a focus of opposing defenses, and while James stopped short of saying that Boston is becoming Rondo’s team, it’s become obvious that he is the main catalyst.

There are many ways and tactics that teams have employed to try to slow Rondo down, but the best and most effective manner takes place on the other end of the floor. If teams make shots, which the Cavs did, then Rondo can’t get out on the break and use his speed in the open floor.

“It’s hard to run when you’re taking the ball out of bounds every time,” Rondo said. “In the first half there were a lot of missed shots. We got easy looks, easy breaks. In the second half it seemed like I was walking the ball up the court every time they made shots.”

Defense leads to offense for the Celtics, but on this night it was just the opposite. No D means no O, and that helps spell the end for Rondo, and the Celtics.

THE PROBLEM WITH FAST BIG MEN

There’s a theory going around the NBA that the way to beat the Celtics is with ultra-fast, ultra-aggressive big men. For proof look no further than the Hawks, who have tortured the Celtics this season with the young legs of Josh Smith, Al Horford and Zaza Pachulia.

When O’Neal left the court in the second quarter, the Cavs were able to counter with lineups including Anderson Varejao, Antawn Jamison and J.J. Hickson. Then there is James, who at a listed weight of 250 pounds is not exactly “small.”

All four players are big and they are all fast and they made life miserable for the Celtics in the second half.

“With Varejao, he puts a lot of energy in the game and keeps a lot of balls alive,” Garnett said. “With the addition of Jamison, he extends their offense. With Shaq, they can’t run [as well] in my estimation. When they have Varejao in there it’s two different teams.”

This is the essential problem for the Celtics for which they might not have an answer. Their front line is big and suitably minded for playing defense against the likes of Dwight Howard, but against the Hawks and this particular Cavs lineup, they have problems.

The issue for Cleveland is, which team will coach Mike Brown use in the playoffs? The Cavs acquired Shaq for the express purpose of defending Howard in the playoffs, but if they are matched up with Atlanta or Boston, will Brown have the nerve to sit the most dominant big man of his era?

The matchups in the Eastern Conference will be fascinating to watch. The Celtics can’t beat the Hawks, the Hawks can’t beat the Magic and the Magic give the Cavs fits.

With Cleveland way out front in the race for the top seed, two games are all that separate the Magic, Celtics and Hawks. How the playoff puzzle comes together down the stretch may be what determines who emerges from that gauntlet and reaches the Finals.

PIERCE SITS, FINALLY

No one who is around the Celtics on a daily basis ever questions Paul Pierce when it comes to playing basketball games. He has shown time and again that he will play through just about everything, and there are times when he even seems to thrive on the pain.

But this season Pierce has undergone knee surgery, severely sprained his foot and injured his thumb. Since the All-Star break he has averaged just over 10 points and three rebounds while shooting 14-for-43. His spirit may have been willing, but his body was definitely telling him to stop.

That left the Celtics in a bit of a bind because his replacement, Marquis Daniels, looked like he should have been starring in a NyQuil commercial instead of getting ready to defend LeBron. Asked if he was going to play before the game, Daniels just grimly nodded.

“I didn’t want to tell him that we need a warm body,” Rivers joked before the game. “Because his body’s already warm.”

It wasn’t like he was being asked to take up space either. James scored 36 points and Daniels did what he could in 30 minutes of action. Afterward Daniels could barely move from his seat in front of his locker.

“He was great,” Rivers said. “He really was. He gave us everything he had and I couldn’t ask for anything more.”

Until Daniels recovers from his bout with the flu, the Celtics are going to be shorthanded, but what else is new? Rivers said that Pierce was going to be out, “the next couple of games.”

The C's play the Nets on Saturday and then don’t play again until Tuesday, so there’s a window for both players to rest and get healthy. The goal has always been to have everyone ready for the playoffs, but the regular season continues to be one big injury report.