Coach Joe Gibbs estimates that as much as 40 percent of the Washington offense, one of the most productive offenses in club history, has been replaced since last season. But even in the midst of this substantial change, he may turn more this year to a once familiar Redskin scheme, the two-back formation.

"We are going to use a lot of two-back sets in the preseason," said Gibbs, who helped salvage last season by moving away from the two-back approach and adopting a one-back, two-tight end alignment.

"There are a lot of reasons for our thinking," he said. "We think it is beneficial to use a two-back offense to teach the entire package during training camp. It helps everyone realize the depth and width of the complete offense.

"But we also would like to take another look at how we do with two backs. We kind of moved away from it last year when things went so well with the one-back approach. Maybe this time, it will work out better for us. That's what we want to see."

There is no reason to believe Washington suddenly will abandon the one-back set as its primary offense. Gibbs also isn't about to give regular season opponents an advantage by revealing all his offensive plans in exhibition games, which is incentive enough at this point to rely more on two-back plays.

"I would think we could use more of it this year but it's always a matter of going with what will work best against the defenses you confront," he said. "Maybe we'll find the two-back is really, really effective. Then you can't look the other way and ignore it. We had so much success with the one-back that teams are bound to try to adjust to it. If they do, we have to have something else ready to come back with.

"It's a matter of giving defenses that much more to worry about. It takes more time to prepare for an offense with a lot of different formations."

Gibbs is one of the pioneers of the one-back set that became so successful at San Diego once the Chargers drafted Kellen Winslow. But in Washington, he is wrestling constantly with the problem of how best to utilize his considerable backfield depth (Joe Washington, John Riggins, Wilbur Jackson, Clarence Harmon, Otis Wonsley and friends), especially considering how much his offensive line has matured since last season.

"One reason that you keep changing an offense so much," Gibbs said, "is to better utilize your personnel. For example, Joe Theismann does a good job rolling out, so you put in more plays utilizing his talent than you would if you had a Dan Fouts. We've had Joe a year now and we have a much better idea of his strengths and how to put them to best use."

But why abandon up to 40 percent of an offense that ranked 10th in the league despite an inexperienced line and crippling injuries?

"There are so many new ideas floating around and so many things that seem attractive to you that it's necessary to keep changing," Gibbs said. "Not everything we did last year worked well. We studied our films and weeded out things we weren't happy with. You just can't stay where you are and be content with the fact you might have done well last year.

"We see things that other teams are doing that work well. If it's a good idea, we'll try it. There are changes in the way patterns are run, the way you block on running plays, or entire parts of your offensive scheme. You gradually shift the offense into other directions just through constant evaluation.

"Sometimes you are forced to change. A new defensive coverage comes into the league, for example. You have to adjust to make sure you can deal with it on offense. Everyone is going to the 3-4 (defense) now instead of the 4-3. You have to devise ways to attack that scheme . . ."

Gibbs' 1981 offense set 13 team records, including total yards, total plays, completions and first downs. Despite a slow start, while in a two-back alignment, the Redskins came within five points of setting a team record for most points in a season.

"People spend all offseason just breaking down opponent films, like our films, to analyze what we've done," Gibbs said. "They've had plenty of time now to look at us carefully. So to keep them guessing, we might put in a shotgun, or more read-screens, or become a read-trap team like Pittsburgh."

But how many of the Redskin changes will be noticed by fans is another question.

"I don't think the things we have altered are that apparent unless you really study us," he said. "I know fans come up to us now and ask why we don't run more screens. Ironically, we probably run as many screens as anyone in the league but we do them differently than people are used to. The problem is, other teams don't waste much time catching on, so it's hard to stay ahead."

Gibbs cut his second draft choice in two days by releasing cornerback Terry Daniels, a 10th round pick from Tennessee . . . Gibbs said he was delighted with the new league rule allowing teams to carry four players on a taxi squad during the regular season. "It gives us a whole different outlook for our (cut-down) plans. It's good for the league and it's good for us; it helps protect you against injuries."