CLEVELAND — Ready for the psychiatrist's couch yet? Or ready to send LeBron James there?

Already plagued by schizophrenia in the series against the Boston Celtics, James played his worst game of the season in the biggest game of the year in the Eastern Conference semifinals Tuesday night.

Those who saw the stunning 120-88 loss to the Celtics in Quicken Loans Arena wondered if they'd watched James' last game in Cleveland. He will become a free agent on July 1 and arguably played in Game 6 like he didn't want to be here.

Leading 3-2, the Celtics can close out the series Thursday night in Boston and eliminate the Cavs from the playoffs for the second time in three years. The Celtics knocked them out in Game 7 of the Eastern Conference semifinals en route to the NBA title in 2008.

In Game 3 on Friday, James looked like the two-time Most Valuable Player, making jumpers rain from all over TD Garden. Then he disappeared for the second consecutive game Tuesday night, making just 3-of-14 shots and totaling just 15 points.

"Of course their defense had a little bit to do with it," James said. "I just missed a lot of open shots I'm capable of making. You don't see it out of me a lot. When it happens, it's a big surprise. They played me the same way they played me all series and I wasn't able to knock down some shots I got some good looks at."

Even though he didn't try driving to the basket until the second quarter, James insisted he hasn't lost his aggressiveness.

"I was still able to get to the free-throw line," he said after making 9-of-12. "We had a great flow. I wasn't able to get anything going offensively for myself, but I was still able to get some rebounds and get some assists and get guys going."

Cavs coach Mike Brown dodged a question on whether James' elbow was hurting.

"It is unlike him," Brown said of James' performance. "He had an off night tonight. He brings it for us almost every night. He tried to bring it tonight, but he was off. He'll be ready to go in Game 6."

James isn't alone in his inconsistency. When the playoffs began, Brown seemed determined to stick with at-most an eight-man rotation, then suddenly discovered long-forgotten Zydrunas Ilgauskas and Daniel Gibson on Tuesday. He couldn't find a way to get Shaquille O'Neal back into the game in the fourth quarter Sunday, but relied on him to carry the team in Game 5.

Early in the series, the two teams seemed content to trade victories and domination on any given night. Asked before the game how he would characterize the first four games, Celtics coach Doc Rivers said, "Rhythmless."

But the Celtics seemed to have discovered theirs, and the result was a shockingly easy romp.

As fans headed for the exits with 5:50 to go, they were tormented by maddening, unanswered questions. Is James gone? And what's wrong with him, anyway?

James' performance against the Celtics was baffling before Game 5. In the Celtics' 10-point victory Sunday, James was outplayed by 38-year-old O'Neal. But in a 29-point Cavs' triumph in Game 3, James set the tempo from the opening tip, pouring in 21 first-quarter points and finishing with 38.

On Tuesday, James looked lethargic again. He didn't score until 10:55 remained in the second quarter, making two free throws. He finished the half with eight points, all from the free-throw line, five rebounds and four assists. He went 0-for-4 from the field (0-for-2 from 3-point range) in the first half and didn't make his first field goal until ramming in a fastbreak dunk midway through the third quarter.

By the end of the third quarter he was 2-for-11 and had removed the sleeve on his right elbow.

Asked what worked so well on James, Celtics forward Kevin Garnett said, "We just changed the looks. A player of his status and his ability, he's so darn good, with some of the schemes we were just trying to slow him down and put an extra body to contest the shots. It's nothing we haven't been doing since we started the series."

But Garnett said James didn't seem frustrated.

"He was very aggressive, ducking his head going to the basket, all the things he usually does," Garnett said. "He started to take over the game, getting fouls and getting and-ones. We did a good job fouling him, contesting his shot and controlling everyone else."

James had only seven games in the regular season in which he scored in the teens and had not been lower than 19 points in the playoffs, that in the series-clinching two-point victory in Game 5 against the Chicago Bulls.

But those who have watched him since his days at St. Vincent-St. Mary are baffled by James' lack of intensity for 48 minutes in the past two games. Usually on nights when his shot isn't falling, he loves being the facilitator, playing Magic Johnson instead of Michael Jordan.

Conspiracy theorists will find plenty to debate.

Is James tired (from two years of nonstop basketball)?

Hurting (from his injured right elbow)?

Unhappy (with what looks like his team's lack of chemistry and the decision-making of Brown)?

Ready to leave town (lured by last weekend's wooing of the New York press)?

Or do the Celtics just have his number?

Even if James had decided to depart in free agency, it seems unlike him to pack it in. He's always been a team-first player, showing no hint of unselfishness on the court.

But the boos were loud at Quicken Loans Arena on Tuesday and James could not be absolved from the blatant displeasure.

While compiling the best record in the NBA, James and the Cavs have been inconsistent all season, trying to switch on their effort when needed.

Owner Dan Gilbert and General Manager Danny Ferry will have to decide if the blame for that erratic desire falls at the feet of Brown or his players. But at least for this night, King James' fingerprints were all over it.