The Redskins, who still are trying to recover from the shock of that dismal loss to the New York Giants Sunday, got another setback yesterday. Coach Joe Gibbs said Joe Washington and John Riggins, his starting running backs, would not play at St. Louis this week.

Gibbs said Washington's injury was diagnosed yesterday as a "turned ankle with fluid behind his Achilles' tendon," a far-less-serious injury than the original report of a partially torn Achilles. Gibbs said the veteran would be out at least two weeks.

Riggins has a badly bruised knee. Gibbs said there was fluid buildup on the knee "and right now I can't see him playing this week. It's a matter of how fast he can come back, but we are planning to go with only four backs this week."

Terry Metcalf, who will be returning to St. Louis for the first time since he left the Cardinals for the Canadian Football League four years ago, will replace Washington. Wilbur Jackson will start for Riggins.

The loss of Riggins and Washington complicates an already shaky situation on offense; the Redskins have scored only 17 points in two games. They have had major problems rushing, which Gibbs said is a key reason for the lack of point production.

Although he received strong support from General Manager Bobby Beathard yesterday, Gibbs admittedly still was trying to recover from "our embarrassing performance" against the Giants.

He admitted the two straight losses have shocked him, that he expected a much better start and that he had overestimated how fast the Redskins were progressing in training camp. It's apparent now that the rebuilding process, which has been slowed greatly by injuries, is going to be much slower than Gibbs and the rest of the organization had estimated at the end of the preseason.

"Sure, this is a surprise to me. I thought we would do a lot better," said Gibbs, in his first year as a head coach after a highly successful career as an assistant. "I can't believe it's happened. The offense was running smoothly in preseason and I thought we were ready. We're making mistakes now we never made during the exhibitions.

"You'd be only human if you have self-doubt at this point. You go through two things. You get angry (at criticism) and you question yourself. The only way to survive self-doubt is to be completely sold on what you are doing. I still am. I believe strongly in our concepts."

Beathard said he is confident Gibbs eventually will produce a winning team.

"Things might not be going like he expected but he can't get down on himself," Beathard said. "I'm sure he's doubting his coaching ability. But he shouldn't. We're on the right track. We can't expect miracles. Things like this take time. But you have to do what you think is right."

Gibbs said he remains puzzled as to why the Redskins have flopped so badly, although he added that he had no plans to simplify his offense or make any drastic personnel changes.

"There is something missing, and I don't know what it is," he said. "Is it repetition? Have we not gone over everything on offense enough? Is it bad breaks? I'm not going to say what else. The worst part is to play that bad, look that bad. It was embarrassing.

"We're going to repeat, repeat, repeat what we have been doing since training camp. We are reevaulating everything, going over everything. We haven't been together that long, but we need to improve our level of performance. That's what bothers me. We have to start showing improvement and we haven't. We've been averaging seven points a game for a long time and we can't do that."

Gibbs said he remained confident in Joe Theismann's ability to handle the offense

"Joe's had a lot of pressure on him these two weeks and he's done some good things," Gibbs said. "And there are some reads that he'd like to have back. It takes time to learn any offense; it comes with repetition. But you don't use that as an excuse for him. He's obviously worried about pass protection; that's bothered him some. But I still feel he has the talent to play well."

Theismann already has passed for 599 yards and established career highs in attempts, completions and yardage. But the Redskins remain the lowest-scoring team in the league, offsetting the outstanding work of the defense, which is ranked first in the NFC.

Gibbs also said:

* Linebacker Monte Coleman (fractured shoulder) would be out at least three weeks and that guard Russ Grimm (cracked knee cartilage) would practice this week to see if his knee holds up. If it doesn't, he will undergo arthroscopic surgery that will sideline him at least two weeks.

* He takes the blame for so many penalties (18) and occasional confusion over special-team and defensive substitutions. "I've said from the very start that penalties can be blamed on poor coaching. And those substitution things were very poor. You can't have that happen. If we have to simplify some things to correct it, we will."

* He's convinced the Redskins have the players "to produce big plays, but no one is doing it. We can't produce (points) when we get close. Instead, we do what it takes to lose. We get in a winning situation, like a back one-on-one with a linebacker, and we aren't coming out ahead."

* The special teams performance dropped off noticeably near the end of the game. But he said he would continue to use Mike Nelms as a kick returner despite Nelms' broken thumb. "He has to be more aware of the cast, but we can't afford not to put him back there."