The word is out in the NBA that the Bullets' have a weak backcourt defense.

"All you have to do is look at the box scores and talk to teams that have played them lately," said New Jersey coach Kevin Loughery. "You'd be crazy not to listen. Their guard defense is awful."

The problem, which has troubled the team all season, has blossomed into a major crisis the last two weeks.

Over the last 15 games, the opponents' leading scorers have been guards. Houston's Calvin Murphy (46 points) and Chicago reserve John Mengelt (27) both set career highs; New Orleans' Slick Watts (26) and the Nets' rookie, Ed Jordan (30), established season bests and Seattle's Dennis Johnson (26) and Atlanta rookie Eddie Johnson (25) had their second-most-productive games of the season.

Coach Dick Motta, who complained at one point "that everyone looks like an all-star against us," is staying outwardly calm. But sources close to the team say he is steaming over the way opposition guards are embarrassing his club night after night.

"I went on record after last season saying we need a strong defensive guard," he said yesterday. "And I still think we do.

"It doesn't surprise me that people are going after us like they are. They aren't dumb. Someone gets hot against us and we can't stop them."

Motta and the Bullets realize that unless they find a remedy, the team will be vulnerable in the playoffs despite its outstanding front line. Injuries and inexperience at guard are limiting the coach's solutions.

The Bullets are satisfied with the the progress Kevin Grevey, a converted forward, is making as a defensive guard, although he still is not as good as the injured Phil Chenier. And they feel Charlie Johnson has done well as Grevey's backup. But both have had their problems against experienced shooting guards.

"Grevey is a forward trying to learn guard," said Loughery, whose guards outscored Washington's, 61-34, Sunday. "He is going to make mistakes and if you are smart, you take advantage of them."

The difficulties are more pronounced at playmaking guard. Tom Henderson has been troubled by season-long ankle sprains and his mobility has become more limited lately. While Motta isn't about to bench Henderson, he has begun lifting him quickly from games if he has early defensive problems.

Motta even has started using rookie Phil Walker, who was languishing at the end of the bench, as Henderson's replacement while Larry Wright, the regular backup playmaker, has been out with a sprained wrist.

Henderson was ill and missed practice yesterday and although Wright's wrist has healed enough for him to play, Motta said Walker would start tonight against Kansas City in Capital Centre if Henderson isn't available.

"I've got to force-feed Grump (Walker)," said Motta. "He's strong and I think he can play defense. I've got to find out in case I need him."

Henderson's future with the Club could well be decided in the remaining eight regular-season games and the ensuing playoffs.

The Bullets need leadership and a strong defensive effort from him over that stand. Otherwise, he could be traded in the offseason.

"Dick wants a scrappy, emotional guard out there who will go after loose balls and play tough defense," said one team source. "This club has needed an on-the-court leader for a long time and it still does. With Motta's offense, you need a guard who will be content to set everyone else up first and get his points later."

Entering this season, Motta was confident Henderson would become "my brains on the floor." But since midseason, when the team was hit by injuries and began losing, most of the play-calling has come from the bench. During that span, the team's fast break also deteriorated.

"Wes Unseld is having a great rebounding season on the defensive boards," said one rival coach, "but they aren't taking advantage of his outlet passes and breaking like they should. Could they use a guy like Kevin Porter?"

Although Henderson refuses to use his ankle problems as an alibi, his friends say the ankles are restricting his mobility and making it difficult for him to keep up with quicker opponents. His shooting also has been affected an in the last seven games he has made only 23 of 70 shots (32 percent).

"He should go in and say, 'Put me in a soft cast for a week and let my ankle heal,'" said a person close to Henderson. "But he knows Motta expects him to be a leader and, with Wright hurt, he feels he has to play.

"The Bullets would be wrong to judge him too harshly or to give up on him. Ever since midseason, both ankles have been killing him."

Henderson first sprained an ankle in a preseason game. He severely sprained the other in mid-January on the start of a West Coast trip that began the Bullets' fall from first place in the Central Division. During that journey. Mitch Kupchak tore ligaments in his thumb and was lost for a month and Chenier entered a hospital with still-lingering back problems.

"Tommy is hurting, I know he is, but he never complains," said Motta. "He went in at half time Sunday and put his leg in the whirlpool to try to get it loose. When Tommy plays well, we play well. I know that too. We need him."

If Henderson's ankles and defense don't come around, Motta apparently will go from game to game with which erer guard - Henderson, Wright or Walker - is most effective defensively while also shooting well.

Wright, still adjusting to the playmaking role, has missed eight games with his injured wrist and his shooting range is limited. He isn't ready for extended duty.

Walker was a shooting guard and defensive center at Millersville State College last year and also has had to learn the playmaking spot. He says he knows what is expected of him now - "He better," said Motta, "because I've told him enough the last week to his face" - and would like the playing time to prove it.

"It's been hard sitting and waiting," Walker said, "But I've kept myself in shape. I think I can play in this league, but it's up to me to show it."

Motta says he isn't looking for a lot of scoring from his playmaker. "They've got to respect his shooting, but mainly I want him to run the break, set up the offense and play defense. If he does those things, this team can win."

Henderson proved that this season. Of his 20 best games, Washington has won 17. And when Wright has come off the bench to score and hand off assists consistently, the Bullets likewise have been tough to beat.

"All you can do is hope the pieces fall into place," said Motta, whose club is 9-6 since opponent's guards have begun their scoring barrage. "I'm not sure of anything right now, the way this season has gone. You just play things day by day."