Sometimes -- oftentimes -- the head games going on in sports are as interesting, and important, as the games themselves.

That's the case now with both of the playoff series involving Boston teams.

In the increasingly-worrisome case of the Bruins, there is the growing concern that they may become only the third team in NHL history to lose a seven-game series after winning the first three.

Captain Zdeno Chara admitted the B's may have been "nervous" in Game Five, even though they were up in the series, 3-1, and were playing on home ice in the Garden, where they had been undefeated (5-0) in the Stanley Cup playoffs.

If the Bruins were "nervous" Monday night, they could be scared you-know-what tonight against the resurgent Flyers in the hostile environs of the Wachovia Center.

And then there's what going on in the Celtics' conference semifinal series with the Cavaliers, in which Cleveland superstar LeBron James was shockingly ineffectual in Game Five, taking just 14 shots and making only three as the Cavs, who had the best record in the NBA in the regular season, were routed on their home court, 120-88.

Whenever such intriguing questions of sports psychology crop up, I turn to the man who's one of the best -- for my money, THE best -- in the business, Dr. Rick Aberman, who's based in the Twin Cities, where he works with the Vikings, Twins, and several teams at the University of Minnesota.

Both the B's and the King, Aberman says, have become "emotionally-reactive."

"Instead of taking responsibility for their own actions," he said of the Bruins, "they're letting Philadelphia dictate to them. They're not really in charge.

"They got up 3-0 for a reason. What they have to do is get back to being who they are and doing what they do. They have to say to themselves: 'We've got to play Bruins hockey, and not worry about the Flyers.' "

It's an old adage -- or even a cliche -- but it's true: Instead of playing to win, the Bruins are playing not to lose. They're playing scared, instead of playing with confidence.

It'll be interesting to see how they play tonight and, if they lose, how they look in Game Seven Friday night in Boston.

King James and the Cavaliers will be in Beantown tomorrow night for Game Six.

After handing the Celts their most lopsided loss in the storied franchise's playoff history in Game Three in the Garden, the Cavs have lost the last two, including a humiliating defeat last night in which James all but disappeared, not scoring his first basket until he dunked a breakaway layup in the third quarter.

James was too passive, Aberman said.

"He allowed the Celtics to determine how he should be. The Cavaliers aren't used to playing with him in that position. With him being shut down, they don't know what to do.

"LeBron James is the Cavaliers," said Aberman. "Without him, the team doesn't exist. It's all about him."

Sometimes, NBA teams will concede a superstar his points and concentrate on stopping his teammates.

In Game Five, the Celts shut down James, and then didn't have to worry about the rest of the Cavaliers.

"I play according to the game and see how it's flowing," James said Tuesday night.

If the Cavs are going to be successful, the game has to flow through him. He was to want the ball -- he has to demand the ball -- every time down the court. Instead of stepping aside, he has to step up.

That's what the greats of the game -- the Michael Jordans, Magic Johnsons, Larry Birds, Kobe Bryants -- against whom James' game will be measured, would do. If they were going to go down, they'd go down shooting.

"Don't be surprised," Aberman said, "if (James) scores 50 in the next game."