Dallas Coach Tom Landry was out of countenance today -- his face was as red, cheery and full of chuckles as old Saint Nick.

If his Cowboys were demolishing Washington here this Sunday, would Landry run up the score if it might knock the Redskins out of the playoffs under NFL's point differential criterion for breaking ties?

"That's speculating," Landry said, "but I hope I'm in that position."

Is he aware of the point parlay necessary in Chicago victory and a Redskin loss to put the Bears in as a wild-card team?

"That's not one of my primary concerns," said Landry, adding mischievously, "but I think it's 33 points."

Would it weigh on Landry that Washington kicked a superfluous field goal with six seconds remaining in their meeting Nov. 18, when the Redskins gloried in 34-20 victory?

"Uuuuummmmmm," said Landry dramatically. "Should that situation arise, which is unlikely, it is possible that I might not be able to control my players. Perhaps that's when Roger (Staubach) will start calling the plays."

Three weeks away from the Redskins has done wonders for Landry's disposition. Once again, he is his usual dour but sly self.

When last seen in Washington, he was a distressed, possibly even confused man with a defending Super Bowl team that even he admitted was "in deep trouble.

"I'm confident of our team again now," said Landry today, his Pokes coming off back-to-back wins over the New York Giants (28-7) and Philadelphia (24-17) and needing a victory Sunday to win a fourth straight NFC East title.

"Our injury situation is even worse now than it was them in Washington. But we're a better team now because our attitude is better and we're closer together."

What Landry means is that he has restored order, thanks to the insight gleaned in RFK Stadium that the Cowboys needed to be grabbed by the scruff of their collective neck.

"Our lowest point of the year came in Washington," said Landry. "The way we lost was sufficient to show me that we had to make some changes."

The next day, Landry fired extroverted linebacker Thomas Henderson -- an omen to all Cowboys to shape up.

"When you finally realize that everything may not come out all right in the end after all, then you decide it's either time to quit or play. We have played," said Landry.

Many people here believe that the Redskin rub-it-in field goal plus Henderson's expulsion from America's team were the sparks that rekindled the cowboys.

"If that kick is what got them started," said Washington Coach Jack Pardee, "them Tom ought to send me a thank you note."

Landry isn't sending any Christmas cards to Dullesville. In fact, he seems to be stealing a bit of Pardee's thunder by taking the initiative in the war of words between these teams.

Before the last meeting, it was Washington's brag -- a growing trademark of Pardee's young, sometimes swaggering Redskins.

Today, in a Washington-to-Dallas press conference telephone hook-up, it was Pardee who was mild as mother's milk. Landry, by contrast, was a touch testy when he was reminded of how several Redskins, led by Coy Bacon did their best to taunt the beaten Cowboys at the end of their first game.

Those gestures and actions may work well for them at home," said the schoolmasterly Landry."But the reaction down here may be a little different.

"But the whole league is more that way now," said Landry, thinking back on Bacon's squirting a water bottle on the Cowboys and Theismann waving a fist in D. D. Lewis' face. "No, I wouldn't exactly call it hotdogging . . . Let's say there's a lot more emotion in the league now."

Lo and behold, look who is as emotional as any team -- feeding off blatant blood lust: the computerized Cowboys. Isn't it Harvey Martin who said after Bacon's taunts, "When the Redskins come down here, we'll bite their heads off."

"I hope," said Laudry, "that Harvey wants to do it that bad come Sunday."

Fortunately, as always, the Cowboys and Redskins will be far more than a duel of words.

The Cowboys have the home field, but they also have gruesome injuries -- safety Randy Hughes scratched while both Drew Pearson and Tony Dorsett are genuinely questionable.

Pearson is an embarrassing symbol of a certain Cowboy airheadness in '79. This is the season when Dallas has forgot how to count to 11. The Cowboys have repeatedly burned themselves by having either 10 or 12 men on the field. Pocket calculators are on every Dallas fan's shopping list: the perfect gift for a Cowboy.

Pearson, however, wins the grubby sweat sock award for damaging his knee cartilage while spiking the ball after a touchdown.

"Drew worries me," said Landry. "He really doesn't look good for Sunday.

His knee is still stiff and swollen."

That's a bonus for the Redskins, who watched No. 88 grab eight passes for 146 yards and two touchdowns in the last game.

Dorsett's presence or absence does not seem to concern either team greatly. Dallas is tired of the dapper dandy's fumbling, and suspects that sub Ron Springs may in time be a more durable, more dependable, if less spectacular 1,000-yard back than Dorsett. For the Redskins, in his three years, Dorsett has helped them almost as much as he has hurt them.

"Dorsett's shoulder is not separated, only bruised," Landry said. "He has soreness and pain, but not injury. It will probably be his decision if he wants to try to stand the pain."

More cruicial perhaps than the absence of a 1,000-yard runner or a 1,000-yard receiver may be the loss of the anonymous Hughes -- a strong link in Dallas' weakest area, the defense backfield.

"There's no question that the defensive secondary is our problem for this game," said Landry, who watched Theismann shred his Aaron-ious cornerbacks -- Aaron Kyle and Aaron Mitchell -- in the last meeting. "We have several options, but I'm not going to discuss what we plan to do."