CLEVELAND — They say NBA playoff series are all about making adjustments, but that’s not completely true for the Celtics as they try to gain a split against the Cavaliers in Game 2 of their Eastern Conference semifinal matchup Monday night.

The Celtics found out in Game 1 what works. They also found out what doesn’t. It was a stark difference in halves as they went from an 11-point lead at halftime to a 101-93 loss, a 19-point swing in all.

There will be small things that they need to clean up and do better, but for the most part the Celtics laid out their blueprint for success in the first half. Now, they just have to do it for 48 minutes, which has been a particularly confounding problem for them to solve this season.

“It’s frustrating,” Paul Pierce said. “I don’t know if there’s an explanation. It’s something that we’ve gotten better at as the playoffs have gone on. I don’t even think about that. It’s the playoffs now. As the series wears on, we’re going to be better in the second half, regardless.”

They have no choice. Doc Rivers was especially bothered by his team’s inability to deal with the Cavaliers second-half run.

“We played well and they attacked us and we didn’t handle it well,” Rivers said. “We have to expect them to make a charge against us.” 

Not surprisingly, Rivers didn’t want to dwell on his team’s successful first half.

“That’s fool's gold. Don’t fall into that,” he said. “They could say they didn’t play well in the first half. At the end of the day, I learned long ago, they want to know why you won. They don’t want to know why you lost.”

The Celtics don’t want to be talking about a loss again Monday night. They know that they have to get one of these games in Cleveland eventually and it would help their chances a whole lot more if it happened sooner, rather than later.

“You don’t ever want to go down 2-0, put yourself in that type of hole, especially against a team like Cleveland,” Pierce said. “The urgency is definitely there. We felt like Game 1 was important, we let it slip away but it’s over, we’ve got to clean those things up. We’ve got to come back with that same mindset, that same type of energy and I think we’ll be all right. We’ve got to play Game 2 like a Game 7.”

Here are five things to focus on as the Celtics try to even the series on the night when LeBron James will be awarded his second straight MVP award.

ALL EYES ON RONDO

Rajon Rondo might have the most difficult job of any player in the playoffs.

On the one hand, he is emerging as the Celtics best player and their best chance to upset Cleveland. On the other hand, he still has to make sure that his teammates — particularly Paul Pierce, Ray Allen and Kevin Garnett — are all involved in the offense.

“It’s difficult,” Rondo said. “I still believe that we have to go through the Big Three. I try to get those guys the ball as much as possible, but at the same time keep [the defense] honest. I guess in the second half that’s exactly what I did, called more movement plays. At the start of the third I was aggressive but after that I wanted the ball to keep moving. I wanted to keep everyone involved.”

The Cavaliers don’t have anyone who can guard him, so they tried three different players — Mo Williams, Anthony Parker and athletic superfreak Jamario Moon in certain situations. Parker earned praise for containing Rondo in the second half after he blitzed Williams for 19 points and eight assists in the first half, but that’s a classic case of a cause and effect.

“We expected everybody [to guard Rondo],” Rivers said. “We assumed either LeBron [James] or Parker. I guess it mattered. Statistically it says that it did.”

Rondo took just two shots and scored just eight points to go with four assists in the second half. And for that, Parker gets the credit. But really, the Celtics didn’t take advantage of the opportunities that were available to them. Some of that is on Rondo, but not all of it.

“It’s a tough one for Rondo because he’s so conscious of Paul and Ray,” Rivers said. “If you have a pick and roll advantage you have to take advantage. I thought he tried to facilitate and the guys didn’t take advantage of it. We didn’t take advantage of what he created and that actually makes Rondo better if we do because then they can’t focus on him as much.”

If there was one overriding truth from Game 1 for the Celtics, it’s that Rondo has a huge mismatch over Williams, and no matter who the Cavs put on him, he has to take it upon himself to carry the load.

“I’m still trying to figure it out,” Rondo said. “It’s hard at times. At first I wasn’t aggressive at all to start the game. As soon as I came out, maybe nine minutes into the game, and came to the sidelines, Doc was telling me to be aggressive. I just tried to turn it on and attack the rim.”

Is there a danger of relying too much on Rondo? A better question might be — as opposed to what?

“He’s a good player and he’s going to have the opportunity to get into the paint,” Rivers said. “Should we say they rely too much on LeBron? You got something going, you stick with it. I thought we should have done it more.”

EXPECT TO SEE MORE KG IN THE POST

Garnett also has a mismatch in the form of Antawn Jamison, who is not a great defender and who is giving up several inches in height and wingspan. The Celtics made a conscious effort to work the ball down low and they put Garnett on the left block more than they usually do.

Garnett scored 18 points on 9-for-20 shooting. The last time Garnett took that many shots in a game was back in November against the Suns in a helter-skelter offensive-minded game. It was also the only time he took that many shots.

“No doubt,” Rivers said when asked if they would keep working Garnett down low. “He’s just got to be aggressive. I thought he started the third quarter being a passer. He’s just so unselfish that it’s really difficult, but he understands that.”

So, once again, we are faced with the eternal paradox of Kevin Garnett. He is a great passer and he and Rondo have worked the two-man game down low as well as any duo in the league at times. He’s also a very good shooter from 20 feet and that opens up all kinds of driving lanes for Rondo, Pierce and Allen.

But in this series Garnett has to be a little selfish. 

“It was really good because he was aggressive and he was attacking but he’s got to stay on that,” Rivers said. “He fights his own self because people don’t get that. They criticize him for being unselfish, which is the craziest thing on earth, but that is who he is.”

IS SHEED ON THE CLOCK?

Rasheed Wallace has said all season that the playoffs are what motivates him, but after a disastrous regular season, the playoffs have been pretty much the same story for the Celtics prized free-agent acquisition.

Wallace picked up three quick fouls in the first half and went 1-for-5 in 13 minutes of Game 1 against the Cavaliers. He was also a liability again on the defensive end where his rotations were slow and his help defense was lacking.

“He has to play better, bottom line,” Rivers said. “He has to play better defense. The offense will come but he has to be a better defender. We can’t wait. He has to play better.”

Rivers elected not to use Shelden Williams despite the heavy foul trouble that Wallace and Glen Davis found themselves in early in the game. That might change, although Rivers didn’t quite his tip his hand on that front.

“He is in the discussion every day,” Rivers said of Williams.

Is he is it more today?

“No,” Rivers answered. “But he definitely is in that discussion.”

HACK-A-SHAQ? NOT QUITE

Shaquille O’Neal didn’t do a lot in Game 1. He got into foul trouble and seemed to bog down the Cavaliers offense and running game when he was on the floor.

But late in the game he showed why they traded for him in the first place. When he gets the ball down low, he is still an unstoppable force. He converted a couple of easy baskets close to the rim in the final five minutes when the Cavs outscored the Celtics, 11-3.

There is one reasonable alternative to allowing Shaq to score so easily: foul him. But that doesn’t mean that the Celtics will go with the Hack-a-Shaq routine and intentionally give fouls.

“No, but I think we should hack Shaq when he has a layup,” Rivers said. “I don’t know about the whole Hack-a-Shaq thing. Honestly, LeBron, Mo Williams all of them. They got layups and they stood. We got layups and we were on the floor.”

Rivers paused for a second and then said, “I’ll stop.”

Speaking of Shaq and hacks…

THE BATTLE LINES ARE DRAWN

Rajon Rondo is on a first-name basis with many of the floors in NBA arenas since he spends so much time there after taking hits on his drives to the basket. Late in the game he took a particularly vicious shot from O’Neal. It wasn’t dirty, but it was tough. Good, hard playoff basketball as they say.

“Shaq has always guarded me like that,” Rondo said. “Going against Shaq, I don’t how much he weighs, but I’m 180. He’s probably double that. That’s probably going to happen nine times out of ten. I’m still going to get back up. It’s not him. It’s the floor.”

Rondo does get bounced around quite a bit. In many ways it’s reminiscent of a young Allen Iverson when he was in his prime with the Sixers. If you’re going to go in there amongst the giants, you’ve got to be prepared to take your lumps.

“I’ve been there before,” Rondo said. “It’s no big deal. You just got to absorb the hit. The thing I worry about is trying to make the free throws. If I make the free throws, I win the battle.”

True enough, but Rondo missed one of those free throws. It was only his second miss on a night when he went to the line 14 times, but the Cavs thought the O’Neal foul did the trick.

“Shaq was terrific,” Mo Williams said after Game 1. “Not only on the offensive end, but on the defensive end, being a presence down there with the hard foul on Rondo. He’d been making free throws all night and you saw the free throw he took after that hard foul. Those little things help.”

Interesting. The Celtics noticed the same thing.

“Rondo’s a tough guy,” Pierce said. “He gets knocked to the floor almost every time he goes the hole. He’s an aggressive guard. As far as it affecting him, I don’t think so. He falls, but he gets back up. The way they foul him, we’ve got to do a better job of doing the same thing and not giving them uncontested layups.”

The Celtics big men got themselves into foul trouble early, particularly the backups. Rivers wants them to use their fouls. He said after Game 1 that he doesn’t care if they foul out in the first half, but he wants them to use them more wisely.

“I’m not trying to take my fouls away,” said Glen Davis who acknowledged that it did take away from his rhythm in Game 1. “If I get three, four, five fouls, we’ve got so many players that can play. Everybody’s just got to step up.”

Or in the case of the Cavs driving to the basket, step down.

This is already a physical series and the teams have acknowledged a mutual dislike for each other. While no one is looking for a Knicks-Heat 90’s steel cage grudge match, Mo Williams probably shouldn’t be looking to get his second dunk in a Cavaliers uniform in Game 2. At least, not without some good, hard playoff basketball-style contact.