After so many weeks of sadness and turmoil, there was nothing but ecstasy in the locker room today after the Redskins drubbed the St. Louis Cardinals, 31-7. Washington's chaotic 1980 football season, begun with so much promise, ended with at least a glimmer of hope for both the franchise and Coach Jack Pardee.

Even the presence in that dressing room of visitor John Riggins, whose retirement triggered many of Pardee's and the team's problems, could not dim the warm feeling generated from the romp over an outclassed Cardinal squad that seemed to lose all hope once it knew injured quarterback Jim Hart could not play.

This was the Redskins' third straight victory, giving them a 6-10 record. While two of those end-of-season triumphs were against weak opponents, owner Jack Kent Cooke will be faced with a difficult decision on Pardee's fate, about which all signs have seemed to point to the coach's dismissal.

"We were able to do things the last three weeks like we could last year," said Pardee, who probably will learn Cooke's decision by Jan. 1. "We were able to get a lot of different people and get all parts of our squad contributing. We just couldn't do that earlier."

Earlier this season, a series of devastating injuries and an inconsistent offense that was struggling to adjust to Riggins' absence turned what Pardee thought was a division title contender into a weak, mistake-prone team that suffered losing streaks of four and five games.

But now, with healthy players and an attack that scored more than 30 points in two of its last three contests, Pardee is left to wonder what might have happened if this were September instead of a bitter cold day in December.

Pardee's unemotional players didn't vow before the game to win one for their beleaguered coach. Nor did they honor him afterward with a game ball; that went to retiring safety Ken Houston. They just quietly went about the business of trouncing the inept Cardinals, whose horrid play at times resembled that of the midseason Redskins.

Without Hart, St. Louis had an offensive offense. Substitute starter Mike Loyd, who played all of the first half and none of the second, did not complete any of his nine passes and the Cards didn't connect on their first throw until 3:39 remained in the third quarter. And that completion, by rookie Rusty Lisch, traveled all of four feet before falling into the hands of fullback Theotis Brown.

The Redskins wound up limiting St. Louis to minus 12 net passing yards, a Washington defensive record. The Cardinal quarterbacks were sacked a season-high nine times for 80 yards in losses. At one point, St. Louis' passing aggregate for the game was minus 54 yards, until Lisch managed six completions. Still, for the day, the Cards were only six for 26, with three interceptions, including two by cornerback Joe Lavender.

While the Cardinals struggled and their impatient fans booed, the Redskins had an impressive first half as quarterback Joe Theismann and his mates picked apart their opponents' injury-weakened defense.

Theismann built a 21-0 intermission lead mainly because halfback Bobby Hammond, starting for Wilbur Jackson, ran well enough (79 yards in the first two quarters, a career-high 135 for the game) to keep the Cardinals off balance.

Once St. Louis began thinking about Hammond's rushes, Theismann's passes became more effective. He drove the Redskins 80 yards in 10 plays for their first touchdown, registered on Clarence Harmon's one-yard run. Hammond picked up 41 yards in that march. Then Theismann completed a marvelous 54-yard scoring pass to Art Monk and finished off the second-quarter flurry with a 15-yard pass to Harmon after fullback Buddy Hardeman had turned a short fling into a 46-yard gain.

A 34-yard Mark Moseley field goal and a two-yard pass to Monk in the second half completed Washington's pointmaking. Monk finished with a team rookie record of 58 receptions, the most by a Redskin since 1973. The Cardinals could counter only with a four-yard touchdown run by Brown in the fourth period, reducing the Redskin point advantage in the season's home-and-home series to 54-7.

Theismann, finishing off his best pro season statistically, completed 19 of 32 for 260 yards. In the first half, when it mattered, he was 14 of 21 for 226.

"Bobby's running set up everything," Theismann said. "You just can't win in this league without a running threat. I don't think they expected us to run that well and once we did, I could do a lot more things. But it was cold out there, very cold, and nothing came easy."

Hammond started in part because of his play last week against the Giants and in part because of Jackson's recent fumbling problems. This was the first time in his five-year career that he has gone over 100 yards.

Cardinal star Ottis Anderson picked up 122 yards, but most of those came long after the outcome was assured by the terrible quarterback play, compounded by a welter of holding penalties. Well into the second half, the Cards contrived to extend Mel Gray's streak of games with pass receptions to 105 by tossing him a three-yard gainer and declining a Redskin offside that would have given St. Louis first and five instead of second and seven.

"I was just glad not to see Hart out there," said defensive end Coy Bacon about the veteran Cardinal quarterback, who has cracked ribs. "He's just terrific. We knew we had to get a lot of pressure on the young guys, make 'em throw fast."

The Redskins did put constant pressure on the quarterbacks, who were hurt further by numerous dropped passes. Linebacker Monte Coleman had three sacks and Bacon two. The others were by Karl Lorch (one), Dallas Hickman (one-half), Rich Milot and Houston, who got in frequently as a nickel back in his last game as a Redskin while flu-ridden cornerback Lemar Parrish sat out the contest.

"If Hart had played, we would have blitzed even more," Coleman said. "The defense and the team needed this win. It gives us something to build on for the future. You like to end a season on a win. It doesn't make up for what's happened to us this year, but it does help a little.

"I'd like to see Jack stay. It's not fair to blame what the players have done wrong on the coach. It wasn't his fault."

The Cardinals never could figure out the Redskin offense. Theismann completed passes to eight receivers, seven of whom had at least two catches. The prettiest play of the day came on the Monk touchdown. The rookie ran a streak pattern down the right sideline but was covered well enough to force Theismann to look down the middle toward tight end Don Warren. That quick glance suckered in safety Ken Greene, who took one step toward Warren. That was enough to free Monk to catch the pass at the five with Greene nowhere in sight.

"It was good to get that one," said Monk, who had only one previous touchdown reception in the NFL. "I knew eventually one would come. I'm just happy I've been able to contribute this season. I never expected to get to play this much, or to catch so many passes."

Things went so well for the Redskins that Pardee was able to substitute liberally in the fourth quarter, a rare occurrence this season. But even against reserves, St. Louis did little to excite the home crowd as the Cardinals finished with a 5-11 record for the second straight year.

"When you are 5-10, it's hard to get up for a game, but I thought the players pushed themselves and did a good job," said Pardee, who somehow has maintained his composure as the pressure grew around him the last month.

"The Cardinals had their problems. But I'm not going to give any win back. We've worked too hard to get 'em this season."