Billy Kilmer will be the quarterback Saturday against the St. Louis Cardinals in the game that George Allen described today as "the biggest we've had in seven years."

Allen continued to insist that he would make his final decision between Kilmer and Joe Theisman at game time, 3:30 p.m. (WTOP-TV-9) in the Busch Stadium ice box.

A defeat will mean elimination from further playoffs contention for either the Redskins or the Cardinals.

When asked about the advantages of starting Kilmer, Allen's point of view became clear.

If I started Kilmer," he said, "it would be the same situation as why as I started Joe before. We have to score some points. We can't beat the Cardinals by scoring one touchdown.

"It's not using anything or anyone as a scapeboat. It's a position of such magnitude where the quarterback's job is to put points on the board. If I have to go that way (make the change), the (Kilmer) has been in a lot of big games for us.

"In the stretch drive last year, he was the quarterback, and he took us in there (to the playoffs. He might have a little more leadership within the team.

He's healthy, he's better than he had been. He's had a rest. If we'd continued playing him, he wouldn't be on the squad today. He was taking a beating.

"Joe is 4-2, and I still have confidence in him. I think he'll be a fine quarterback. And Kilmer's a heck of a quarterback. It's a tough decision to make whatever way I go."

Allen is also going to Kilmer because of past performances. Kilmer produced season highs of 24 points and three touchdowns in the last game between the teams, a 24-14 Washington victory. And with a wildcard berth still a stake. Allen is going with brains, floating passses and experience over young legs, a rifle arm and errastic play-calling.

The playoff situation is still extremely complicated. The Redskins still not win the wild-card spot, depending on how the Minnesoat Vikings and Chicago Bears finish up. But a loss Saturday by the Redskins or Cardinals means instant elimination.

Meanwhile, both quarterbacks declined to talk about the switch, although Theismann did admit he was being demoted in a television interview Thursday night.

"I have nothing to say about anything," said Theismann. "If there's any questions to ask, coach will answer them."

Kilmer, who has been telling repoters. "I have nothing to say," most of the season, was a bit more verbose today. "Don't talk to me," he said. "Talk to coach Allen. You didn't talk to me all year; don't come around now."

Allen and his coaching staff of course, are gambling that the Redskins' mostly moribund offense will come around Saturday against a Cardinal team that has lost four of the last five games between the teams, three in a row, and that was bombed the last two weeks, by Miami and the Giants.

Despite Kilmer's presence, the oddsmakers are saying the Cardinals are still favored by four points, mostly because of the home-field advantage and the usual big-play St. Louis offense, even if it has suddenly gone bust.

But the Redskins are hurting on defense. Defensive tackle Bill Brundige has not practiced all week and will need a special arch and a pain-killing shot just to trot out onto the concrete-like artificial turf in cold (20-degree) Busch Stadium.

"I'll play," Brundige insisted today. "If I don't, we might have to go to the 3-4 defense, with three down linemen and four linebackers).)

Allen is hoping that Brundige and his defensive mates do not have to be on the field that long, another reason for starting the more patient, ball-control-oriented Kilmer.

"The offense has to keep (Jim) Hart (Terry) Metcalf and (Mel) Gray and that gang off the field," Allen said. "It's very important that we move the ball on the ground and in the air.

"When St. Louis has lost two teams like Miami and New York, those teams have controlled the football. And when Hart goes in, he has to get it back in a hurry. Sometimes he throws interceptions, they make mistakes and he becomes frustrated."

Over the last three years, the Redskins have managed to defense the cardinals' big-play men quite adequately.

Hart, a 50 per cent career passer and 54 per cent this season, has only connected on 47 per cent of his throws against the Redskins in the last five games, and has thrown a total of 10 interceptions.

"The key there is to pressure him," said Redskin secondary coach Ralph Hawkins. "If you don't. he'll kill you. We don't sack him very often but we have put some heat on him."

The Redskins have also made it difficult for Gray, the swifty wide receiver who is the Cardinals' leading receiver this year with 3-4 catches and a 21-yard-per-reception average.

Gray caught only three passes in the last meeting of the teams his average production in the five previous Redskins-Cardinal games.

"We want to jam him - stop his momentum coming downfield and try to take him off his timing," said Hawkins. "We'll change coverages on him and give him double coverage in situations we think he's more inclined to catch the ball. And you also have to be a little lucky."