It all began before the season, when Redskin defensive coaches decided, as assistant Richie Petitbon put it, "if you can't hit home runs, you better win by doing something else, like stealing bases."

The coaches knew Washington defenders could not line up every week using standard tactics and expect to be successful. So they adjusted, and from all the tinkering, the most daring and perhaps the best secondary in pro football has emerged.

Simply put, the Redskins are using their defensive backs to make all 11 players on the defensive unit better performers. Any innovations and any special tricks have started first in the secondary.

In the process, the Redskins have reversed a football adage that good pass defense is produced by a good pass rush. For the Redskins, outstanding secondary play is most responsible for the improved pass rush the last few weeks.

With cornerbacks Joe Lavender and Lemar Parrish tormenting wide receivers by using physical, man-to-man coverage, pass patterns have taken longer to unfold, giving the front four more time to reach the quarterback. The result has been a league- best 12 interceptions and an overall defense which has allowed only 14 points in the last three games.

"This is the best secondary I've ever been associated with," said strong safety Ken Houston, a 13-year veteran enjoying another successful year.

Coach Jack Pardee isn't ready to go that far, although he acknowledges "for what we are doing, they are really good. But the Los Angeles secondary, which plays in a more standard defense, might be the best. It's just hard to compare the two."

Probably no other team in the NFL is playing as much man-to-man with its cornerbacks, a move caused in part, according to Petitbon, "by the new rules on chucking receivers. If you can't delay them, it makes it easier for them to get down field and into an open area against a zone. If you don't play man to man, you'll get killed."

But the Redskins feel they would be foolish going up against a strong opponent such as Philadelphia on Sunday, not having Lavender and Parrish in man-to-man coverage. As far as Petitbon is concerned, both are playing at an All-Pro level.

"Lemar is maybe the best around, he just has to be the best," Petitbon said, "and Joe Lavender has never played better. This is his best season. He's more aggressive, he's quicker, he's just doing everything we ask."

With Houston as dependable as always, another key to success has been the emergence of free safety Mark Murphy, who replaced Jake Scott this season. Murphy has given the secondary an emergency valve that has made it easier for the other three members to sleep at night.

"Muphy lets us gamble, he lets us be more aggressive," Lavender said. "You know that if you get beat, he is always going to be there to protect you. He never bites and comes up too fast and he never tries for a daring interception. He's smart and we can depend on him."

Dependability was perhaps the major reason the Redskins decided to go with Murphy, who had been on the field for five plays as a pro at free safety, and release Scott, who had a team-high seven interceptions last season. As good as Scott could be, he gambled too much and missed too many tackles.

In contrast, Houston says Murphy "hardly ever blows an assignment and I think he is the hardest tackler on the team." Says Petitbon: "You can't believe how many big tackles Mark has made for us so far. He's living up to our expectations and he'll get better."

The Redskins think so much of Murphy's intelligence that they have made him the secondary quarterback, barking out alignment changes once the opponent's offense arrives at the line of scrimmage.

"Intelligence maybe is the one constant trait of the secondary," Petitbon said. "We ask a lot of them and they do it with hardly any mistakes. They know their assignments and they are usually are in the right position at the right time."

Parrish always has been in the right place at the right time. Tops in the NFL with five interceptions, he is enjoying what Petitbon calls "a great year produced by a great player. And how good can that be? I'll tell you this, I wouldn't want to make a living depending on beating him every week."

Parrish is so quick and so physically gifted that he can make mistakes and still recover in time to pull off a big play.

"He can do things that I only dream about," said an admiring Lavender. "His reactions are incredible. The things he does, he does every day in practice, too. Nothing surprises us."

Lavender, the tall member of this Mutt and Jeff cornerback duo, says he depends "much more on technique. I have to make sure I'm doing every movement correctly. If I make a mistake, I can't get back like Lee can."

But Lavender has swallowed a big bite of Parrish's aggressiveness. He is more daring, willing to take on opponents head up at the line of scrimmage and hit them long before they get into a pattern.

"How can someone get more aggressive? Well, as a coach, you just push and ask until you get it," Petitbon said. "Joe realizes what we need him to do to win and he's responding."

Two other factors have helped Lavender. He is 10 pounds lighter this season (190 compared to a normal 200) after off-season stomach surgery. And the Redskins are putting less emphasis on complicated assignments and more on natural instinct.

"I never would think I should play at 190 but I feel quicker and more alert," said Lavender, who has, in Parrish's estimation, "the quickest feet of any cornerback around." Lavender says he has benefitted "from fewer changes in our assignments. Once we call a defense, we are sticking with it.

"Knowing that, I don't have to sit back and worry about making changes. I can get in there and concentrate on my man."

That's what the defensive coaches want. "In the past," Petitbon said, "the Redskins relied so much on finesse. They wanted to be in the perfect defense for every play. We are thinking less and playing more recklessly. We're more aggressive. We are making things happen because of this style."

Houston has become a major catalyst in forcing a lot of the mistakes. Against the Houston Oilers, he was a second middle linebacker. Against St. Louis, he was a blitzer who forced two fumbles. He remains an intelligent, conscientious performer and the acknowledged on-field leader not only of the secondary but of the entire defense.

This season, the secondary also has unprecedented depth. Rookie Ray Waddy has emerged as a surprisingly talented nickle back while safety Tony Peters, obtained in a trade from Cleveland, probably would be starting for many teams. He is heir apparent for Houston's job.

"We are still on the upgrade," Houston said. "The longer we play together, the better we'll get. It also helps that everyone likes each other. That way, no one is hoping somebody else messes up. And that does make a difference."

Center Ted Fritsch's father died unexpectedly Thursday night. Fritsch missed practice yesterday but is expected to be in Philadelphia Sunday . . . Bob Kuziel practiced long snaps in Fritsch's place . . . Both Ricky Thompson and Danny Buggs continued to recover from their injuries but Pardee said he wasn't sure whether either would play against the Eagles.