Despite all the talk about revenge, momentum and pride, the outcome of Sunday's NFC East title game comes down to the performances of two players: Joe Theismann and Roger Staubach.

"Joey has to play well," said Joe Walton, Washington offensive coordinator who will call the plays for Theismann. "You know Staubach will do his job -- he always does. But Joe can compete with him; we have confidence in him."

Staubach's trophy case is loaded with mementoes of victories in big games like this. For Theismann, Sunday's 4 p.m. game (WDVM-TV-9) is the biggest test of his pro career.

To overcome Dallas' home-field advantage and to nullify the Cowboys' well chronicled ability to win the most important regular-season games, Theismann will have to be consistent, durable and capable of standing up under what could be a tough pass rush.

And Washington must force Staubach out of a game plan that mixes runs and passes equally. The Redskins want him to throw, and they will try to force enough mistakes to nullify any big-yardage day on his part.

So much depends on which quarterback can carry the day. To the victor goes the NFC East title and the home-field advantage in the playoffs until the Super Bowl. If the Cowboys lose they are still in the playoffs as a wild-card team. If the Redskins fall, take out the calculators and follow along:

Washington will go on to postseason play no matter what else happens Sunday as long as Chicago loses to St. Louis. If the Bears win, however, the final NFC wild-card berth will depend on total net points this season. The Redskins take a 33-point lead over Chicago into this final weekend.

There is also an asterisk to all this. If Chicago wins and Tampa Bay loses, the Bears are the NFC Central champs. Since the Bucs are out of the wild-card running, the Redskins then would be in the playoffs, even if they lose big to the Cowboys.

By game time, the Redskins will justabout know where they stand in this playoff. And that brings up another interesting point. What if late in the game, Coach Jack Pardee finds himself in a situation where kicking a field goal would guarantee a playoff spost while going for a touchdown would beat the Cowboys?

"I'm not even going to think about that," Pardee said."We are going down there to win and I think we can. We will face things as they come in the game."

This has been a fun-filled week for fans from both cities. A massive press buildup has renewed a rivalry that George Allen made famous during the early 1970s. Yet the Redskins still have the impression that even a 10-5 record hasn't earned total respect from either the oddsmakers or the Cowboys.

Otherwise, the Redskins ask, why are they 9-point underdogs? And why do the Cowboys seem so sure they are going to reverse the 34-20 defeat handed them by Washington a month ago in RFK Stadium in a game that left Dallas fuming over a roll-up-the-points field goal.

"All of this makes you wonder," said Theismann, who had a shocker himself this week when he was left off the NFC Pro Bowl team despite sparkling credentials. "Guess we have to prove again that what we have done this season is no fluke."

Of course, no one thought Washington would be playing for anything but pride by the 16th week of the schedule. And even now, it doesn't seem possible that his club of free agents, no names and aging veterans, which starts one of its own draft choices, could compete against the big-name Cowboys, even if the Dallas has injury problems.

Dallas halfback Tony Dorsett and wide receiver Drew Pearson still are considered questionable but Pardee expects to see them in the game. He feels rookie cornerbaack Aaron Mitchell, not Dennis Thurman, will start at cornerback while Benny Barnes takes over for Randy Hughes at safety.

Theismann will likely test the weakened Dallas secondary frequently. With fewer injuries, the Cowboys gave up 210 yards passing and three touchdown passes in the first meeting and now even their reliable nickel defense has been shaken up.

"You always try to go on their cornerback," said Walto. "Tom Landry is a man-to-man coach and that can backfire on them. I think we can move the ball through the air but I also think we have to run, too. We've got to keep them off balance."

The Reskins would like to gain from 100 to 125 yards on the ground, just enough to make Harvey Martin and Co. think about John Riggins. And that will give Theismann more time to pass.

Martin's tacklemate, All-Pro Randy White, was hobbling on a sore foot at RFK Stadium but he's healthier now. His matchup against guard Ron Saul, a gutty player but not as quick or as strong as White, is important to the Redskins' chances. Saul most likely will get double-team help from center Bob Kuziel, which leaves tackel Terry Hermeling alone on Martin.

"Our offensive line has to hold up," Pardee said. "We did a good job in the first game (giving up two sacks) but I'm sure the Cowboys will be coming a lot stronger this time."

Theismann also will probe the Cowboys' new left linebacker, Mike Hegman, who replaced Hollywood Henderson. Last week, the Eagles burned Hegman, on passes to their backs, which also is a Redskin specialty.

Despite their nagging problems, the Cowboys are dangerous as long as Staubach can walk. Even against Philadelphia, when his passes wobbled and he threw repeatedly into double coverage, the Dallas quarterback played well enough to pull his club to a much-needed victory.

He had a troublesome afternoon at RFK, throwing three interceptions and being sacked three times. His 276 passing yards were impressive, but Theismann stole the day with better consistency.

Still, Staubach has had a splendid season, probably one of his best. He has thrown for a career-high 3,250 yards, completing 58 percent of his tosses, and he ranks No. 1 among NFL quarterbacks. Not bad for a 37-year-old.

"What we can't let happen," said free safety Mark Murphy, "is for Roger to burn us with bombs. That's how they get you. They score quickly, and they do it with long plays. If we make them work for everything they get, we should be okay."

This is a mistake-prone Cowboy team, even if Dorsett (of the sometimes-stone fingers) is sidelined. But if they get ahead early, get the feel the kill, then watch how tightly they hold onto the football.

"We can't let them have a quick start," Riggins said. "They're a notorious frontrunning team. Always have been. We just can't make mistakes and let them get going. We have to be near perfect."

Washington thrives on turnovers. Without them, the Redskin offense is forces to put together long drives, and that is not a strength of this team. Washington's defense also has functioned best when it has mounted a good pass rush, as it did with six sacks in the first Cowboy game. Without exerting pressure, the unit can be picked by Staubach.

"Another big key for us in Joe Lavender," Pardee said. "With Pearson and Tony Hill, they have two great wide receivers, Joe and Lemar Parrish have to hold up against them."

There are other factors, but neither coach can judge those until the game starts. Will the Cowboys play with rare emotion, remembering the field goal? Can the Redskin old-timers get up for one more game, just as they did in fine efforts against Philadelphia and Dallas at RFK? Will Washington be hurt by the artifical turf?

And will Theismann, finding new football life at age 30, use this afternoon to serve notice to the rest of the league that another full-fledged quarterback star has arrived?

"I'm approaching this like any other game," Theismann said. "I know what is at stake, but we've been successful this season doing certain things and preparing in certain ways and there is no reason to change now.

"We just want to take what they give us. We want to have balance between the run and the pass and we want to be consistent. That's what I've tired to do all season and I hope I can continue it."

Staubach is used to the pressure generated by a game like this. Theismann is still learning, but Walton thinks now he is ready for graduation.

"Joe is dealing with a lot of new things," Walton said, "How to handle pressure, how to come back from bad plays, how to rally a team. Roger has done all that. Joe has to show now he can, too."

If Theismann can come through, if he can show he is Staubach's equal on the enemy's home turf, the Redskins have a decent chance of winning.

If he can't, Washington probably will have to be satisfied with a wild-card berth, which isn't a bad consolation prize.

The Redskins worked out briefly at Texas Stadium today . . . Pardee decided not to activate kick-returner Buddy Hardeman, mainly because he didn't want to shake up his roster at the last minute . . . This will be Washington's first Sunday afternoon national TV game this year, a reflection on the Redskins' preseason expectations.