The in football joke in New Orleans these days concerns "big games."

"Sure, we've played big games before, but those were when your grandparents came to see you play," said Archie Manning, the quarterback of New Orleans' wide-open offense.

The Saints (4-4) have won all but one of their last five games and come to Washington (6-2) Sunday tied for the lead with Los Angeles in the NFC West. Since the team began in 1966, the Saints never have had a winning season.

If we played Washington five years ago, it was only a big game for us because they were playoff contenders and we had a chance to upset them," Manning said. "We're past midseason now and we're having big games. In the past, we were out of it by now."

For Washington fans grown accustomed to watching Wilbert Montgomery and the ball-control Eagles two of the past three weeks, these Saints also have a standout runner -- in fact, two of them -- and a solid quarterback. But New Orleans also prides itself on wide-open offense.

"Playing a team like this, you've got to use pretty good (defensive) balance in your deployment of all your players," said Redskin Coach Jack Pardee. "They've got so much speed, so much explosive power. They have ol' Wes Chandler, Chuck Muncie, Tony Galbreath, Henry Childs, even Ike Harris, guys who can score from any place on the field."

Manning was voted NFC player of the year last season by the Sporting News and United Press International after the nine-year veteran completed 61 percent of his passes for a whopping 3,416 yards -- besides scrambling for 202 yards on 38 carries.

Halfway through the 1979 season, Manning has completed 60 percent of his passes for 1,735 yards. He has a healthy offensive line (three starters, including guard Conrad Dobler; had gone down by the third game of last year's best-ever 7-9 campaign).

Last year, his two 220-pound running backs, Muncie (557 yards in 160 carries) and Galbreath (635 yards in 186 attempts), gained only 1,192 yards in 16 games. At midseason now, they have 1,065 yards in 114 fewer carries.

"At the start of the season, the defense was slow out of the blocks, and so we chalked up a lot of passing yardage," Manning said. "Now they've come along and we've run the ball."

For Manning, this is quarterback utopia, even though he has thrown 15 interceptions, most in the NFC. $"Strictly as a quarterback, you've got to have confidence in both your passing game and your running game. Last year, I put a lot of pressure on myself because I thought we had to pass. "This year, I feel a lot better going into the ball game, because we have better balance."

The Saints have the second best offense in the NFC behind the Cowboys. They have scored 197 points and probably reached maximum efficiency two weeks ago in the second half against the Tampa Bay Buccaneers, the NFC's top defensive team at the time. After a scoreless first half, the Saints scored on six straight possessions and won, 42-14.

The opening three losses were not entirely the fault of the defense, which has six players now who did not start the season -- partly because of injury, partly because of performance. The Saints also lost Russell Erxleben, their No. 1 draft choice, to a leg injury, so they did not have a legitimate field goal kicker for one game.

Since then, the Saints have signed Garo Yepremian, who sets a record for consecutive field goals every time he connects. He has 20 straight, a streak he started in Miami last season.

The Saints use the 4-3 flex defense, the only team in the NFL to do so besides the Cowboys. They have intercepted 14 passes the last five games for a season total of 16, best in the NFL.

The Saints opened the season with three of their four regular secondary players out injured. When strong safety Ray Brown, right cornerback Eric Felton and left cornerback Clarence Chapman were able to play, free safety Tom Myers, a hard hitter who would get national recognition on a better team, missed one game, against Los Angeles, with a knee injury.

That was the only loss in the Saints' last five games. Pat Haden, the Ram quarterback, said Myers "means so much to the Saints' defense. So much of our preparation is directed at trying to beat him."

The loss of Brown for four games also was important, especially because the Saint's use the flex.

"The strong safety is the key guy when playing the flex," Manning said. "Ray Brown is to us like Ken Houston is to Washington. He's just a big part of our pass and rushing defense."

Three other players have moved in as defensive starters since the season began. An injury has put second-year man Barry Bennett at left tackle. Don Reese has beaten out former Maryland star Joe Campbell at right end, and Ken Bordelon has replaced Jim Merlo at left linebacker.

Besides Myers, the Saints have one other outstanding defensive player, middle linebacker Joe Federspiel.

So, the players are talking about big games for real for the first time this late in a season and the city of New Orleans is feverishly talking playoffs.

Linebacker Rich Milot practiced yesterday for the first time since breaking his wrist two weeks ago against the Cleveland Browns. Pete Wysocki remains the starting right linebacker, but Milot may be able to play on some special teams this week. He has been fitted with a fiberglass cast and says the pain has subsided. The Redskins list him as questionable . . . Guard Ron Saul missed his first practice of the season because of a sprained right ankle. He also is listed as questionable. Fred Dean replaced him . . . Tony Peters continued to work at right cornerback and Joe Lavender is listed as doubtful with a knee injury. Pardee said that if Lavender played any position other than cornerback, where changing direction while running is so vital, he probably would be able to play . . . The Redskins lead the NFL in turnover differential, with a plus 12 . . . The high winds and nippy temperatures made it difficult to work on passing, but Pardee termed the first major practice for the Saints a pretty good workout.