There probably are as many theories about how well the revitalized Redskins will play this season as there are waves in Joe Theismann's styled hair.

The We'll-Back-Over-Them Theory: With a born-again backfield of John Riggins, Joe Washington, Wilbur Jackson and Terry Metcalf, coupled with Joe Gibbs' gung-ho offense and Theismann's strong preseason showing, the Redskins can't resemble the 6-10 bunch of last year that was 25th in the league in scoring and 23rd in total offense. Since the defense can't be any worse, why not a winning record?

The League-Is-Mediocre-So-Just-Stay-Healthy Theory: Of the Redskins' opponents, only the Eagles and Cowboys are deeper in quality players. If the Redskins stay healthy and win their home games, isn't a wild-card playoff berth challenge possible?

The Ken Beatrice They-Can't-Play Theory: The Redskins are slow, Metcalf really isn't very good, most of the players are average, the defensive line is out of step, the linebacking has no depth and how can you throw the ball if your offensive line can't pass block? If Washington is 8-8, it'll be a miracle.

The Once-the-Offensive-Line-Sheds-Its-Diapers Theory: The Redskins will be only as good as the offensive line makes them. The backfield is sound, the wide receivers adequate and Richie Petitbon's influence will stabilize the defense. But until the line matures (and stays healthy), even Gibbs won't be sure how his club will play from week to week. Anything from 6-10 to 10-6 is possible.

The winner: The Diaper Theory, but it may not wash.

There is no question the offensive line remains the most conspicuous unplaced piece in Gibbs' team puzzle. If the line falters, it will negate all the heralded changes the Redskins have undergone since January to alter both the character and fiber of this franchise.

It probably is highly presumptuous of the club to think a line likely starting two rookies and two others with only rookie experience should be able to hold up through a first-half schedule that opens with Dallas and includes Philadelphia, New England and games at Chicago and Miami. But could this line be any more inconsistent than the one that allowed 36 sacks last year?

"No question the line is our key concern," said Gibbs, the former San Diego offensive coordinator about to embark on his first head coaching job. "Lines in this league take a long time to develop. It's the toughest position, I think, to play. We've got a lot of talent there and it will be good, but I don't know how soon."

It didn't help Gibbs' disposition much during camp to have the bulk of injuries concentrated within that line. Young players missed valuable practice work, but Joe Bugel, the offensive coordinator, insists he can have a competent unit quickly with tackles George Starke (the only veteran) and rookie Mark May (the No. 1 draft choice), guards Melvin Jones (who spent his rookie season on injured reserve) and rookie Russ Grimm (the No. 3 pick) or Jerry Scanlan (a second-year converted tackle) and center Jeff Bostic (whose only experience has been snapping on kicks).

If Bugel is right, good things could happen. The team should be much more interesting and aggressive under the leadership of Gibbs, the first offensive-minded coach the Redskins have employed since George Allen came on the scene.

Gibbs, who was brought in to replace popular Jack Pardee, has restructured the squad. Familiar players such as Diron Talbert, Pete Wysocki, Terry Hermeling, Dallas Hickman, Ken Houston and Bob Kuziel have been replaced by rookies, young veterans and newcomers such as Joe Washington, Metcalf and Mike Rae. This has become the youngest Redskin team since the Over-the-Hill gang rode into town 10 years ago.

Third-year players Rich Milot, Monte Coleman and Neal Olkewicz start at linebacker, rookie Tom Flick is Theismann's backup, second-year wide receiver Art Monk could develop into one of the league's best and rookie receiver Charlie Brown and second-year defensive end Mat Mendenhall could play important roles throughout the season.

Monk, Brown and Ricky Thompson are the major figures in a receiving corps whose reputation hardly is keeping secondaries awake at night. Yet Gibbs' passing philosophy and Dan Henning's coaching could make this group a pleasant surprise. If the receivers falter, it will be tough for the offense to flourish.

The same can be said if Theismann, who has been staggered by the club's refusal to negotiate a new contract, doesn't have the kind of standout season he wants. His defensive reads and throwing accuracy are crucial to the offense. He also lends much-needed maturity. It is hard to overrate his importance and the way he has adapted to Gibbs' teaching. But how deeply will his performance be affected by his off-field troubles with management?

The way all the new running backs have fit in has been an on-field surprise. Metcalf, who some thought was washed up, seems as quick as ever, and Joe Washington has looked every bit as good as his clippings. Add the comeback of Riggins from his year's layoff because of a contract dispute and the Redskins may be able to move up the middle as well as outside for a change.

Petitbon will have his defense gambling more, with blitzes, stunts and specialized playing. He'll shuffle personnel, especially along the line, where he will try to get the best of both pass and rush defense from the likes of Young, Mendenhall, Dave Butz (who has had a fine preseason), Karl Lorch, rookie Dexter Manley and ancient Coy Bacon. Unless this front line stabilizes, a lot of Petitbon's tactics will be undercut.

The Redskins want to be stronger against the run (they were next to last in the league in 1980), increase their sack total (44 in 1980) and maintain their stingy play against the pass (first in the league). The secondary of cornerbacks Lemar Parrish and Joe Lavender and safeties Mark Murphy and Tony Peters is superb; the expected return of Brad Dusek would add depth at linebacker, where Coleman is being counted on to produce big plays this season and Olkewicz already has shown improvement in the middle.

The 1980 season produced plenty of sloppy, unintelligent play (36 turnovers and 1,080 yards in penalties, second in the league) and losses. "We're going to try to be smarter," said Gibbs, who cuts off any predictions beyond "I want to win all eight home games.

"I'm encouraged by what I've seen so far, I really am," he said. "We want to be exciting and sound and we'd like to win. That's a tall order, I guess, for any team, considering the changes we've had here."