Redskins Coach Joe Gibbs remained convinced yesterday that Washington's drive for home-field advantage in the playoffs is about to receive a boost from an offense that has scored only three touchdowns in the last four games.

"I'm sure that what is happening to us (on offense) is a series of circumstances and that those circumstances will soon come back in our favor," Gibbs said.

"The plays are there, but something happens to mess them up," he said. "A ball is batted down when a receiver is wide open, a fumble at the two yard line . . . that's what keeps you from getting extra touchdowns.

"It remains a tremendous concern. The players are aware of it and we work on it hard. We have good game plans around the goal line . . . But (soon) we'll get a right cut and John Riggins will go into the end zone or Art Monk won't drop a fade (pass)."

"You hope right now it's the little things that are happening to us. I'm convinced over the course of the season that these things even out, that they will start going our way."

In the last four games, the Redskins depended heavily on the strong fourth-quarter running of John Riggins and Mark Moseley's field-goal kicking to win. During that span, their defense has played increasingly better, the major reason the team has stayed close enough to allow Moseley, who has made 18 straight field goals this season, to be effective.

Gibbs realizes he can't expect Moseley to be unerring forever, which is pressure enough to get the offense functioning smoothly. But even though he has talked about giving Joe Washington more work, he said yesterday that he wouldn't change an offensive pattern that has helped the Redskins clinch a playoff spot with a 6-1 record.

Washington, who had seven touchdowns last season, is the Redskins' quickest runner and only big-play backfield threat. But until he turned a broken play into a 22-yard score against the Giants Sunday, he had not been in the end zone this year.

"John Riggins is our first-down running back and he's the guy who keeps us rolling," Gibbs said. "Joe Washington is the back who goes in during any other situation but running downs. He can play more than that but my feeling is that we will stay with John.

"A lot of our success has come from time of possession and the ability to run the ball. That helps our defense by keeping them fresh. Those are the things we have to keep in mind. Besides, we have had great success scoring something inside the 20. Only twice (in 24 attempts) have we not come away with at least a field goal this season. That has a tremendous effect on the team."

Riggins has become the key to the ball-control offense, carrying 168 times this shortened season. In contrast, Joe Washington has only 16 attempts.

Ability to run is essential to the Redskins' winning success. In the last two years, they have won seven straight games in which they have had at least 30 rushing attempts. When they are forced to pass more, they generally have lost since Gibbs became their coach last season.

"We aren't being more conservative because of Mark's field goals," Gibbs said, "although we don't want to waste our scoring chances either. There's no question we'd like to make things easier on ourselves, but the main thing is we are winning."

Gibbs also praised Joe Theismann's play against the Giants, even though his quarterback threw four interceptions to give him nine in four weeks.

"A lot of quarterbacks have come in after a half he had and just quit," Gibbs said. "But Joe, in the second half, was reading his keys and throwing very well. You sometimes get more respect for a person when something bad goes on than when something good happens . . . Other than Dallas and the Giants, he's played very consistently in every game. He knows when he throws interceptions, our odds of winning go out the window. He's very aware of that." Concerning other matters, Gibbs said:

The Redskins' No. 1 goal now is to be the first seed in the NFC playoff bracket. "I really think we have a home-field advantage in RFK," he said, referring to the stadium's grass field.

He hopes two good fourth-period punts by Jeff Hayes will help the rookie kicker's confidence and snap him out of a prolonged slump.

He doesn't consider his team lucky or charmed. "A lot of what happens to us is unlucky," he said. "We sit in there and fight hard and keep the ball longer than other people."

He still is haunted by the Redskins' 0-5 start last season. "That sticks in the back of your mind and motivates you and pushes you," he said. "It's something you'll never forget."

The Redskins replaced tight end Mike Williams, who underwent knee surgery yesterday, with veteran Rich Caster, who was cut in training camp after playing with them last year. Williams, a fifth round choice from Alabama A & M, was a starter early in the season, but has been playing sparingly behind Rick Walker. "The strike hurt Mike, he was in a groove and he got out of it," Gibbs said . . . The Redskins believe cornerback Joe Lavender, who sprained a knee Sunday, will be ready for New Orleans this week. If not, LeCharls McDaniel will be the new nickel back.