Joe Theismann has a simple way to sort out the myriad of Redskins offensive changes for today's opening-round NFC playoff game against the Detroit Lions.

"I'm just asking the guys in the huddle to wear name and position tags, so I know who's who and who's playing where," Theismann said.

It will be up to Theismann to cope with all these changes. Otherwise, Washington's injury-riddled offense could have a difficult time against the 5 1/2-point underdog Lions (4-5) in this 12:30 p.m. game at RFK Stadium (WDVM-TV-9, WMAL-630).

Although for most of the season few of their players were hurt, the No. 1-seeded Redskins (8-1) are far from healthy for their first playoff game since 1976. Coach Joe Gibbs thinks he knows who can play today, but he won't be sure until after pregame warmups.

"I expect John Riggins (thigh pull) to start," Gibbs said yesterday. "Of course, Art Monk (broken bone in foot) is out and Alvin Garrett will replace him. I think Joe Washington (sore knee) will play, but we will have to see how he feels. Even though he hasn't worked much all week, he's been around enough to still be effective. I don't think we'll get much, if anything, from Clarence Harmon (sore knee, cracked bone in hand)."

As a precaution, the Redskins finally activated Wilbur Jackson off the injured reserve list, replacing him with Monk. That means Monk officially is out for the rest of the playoffs. Jackson says he expects to play mostly on special teams, but he also is available if Washington's knee acts up.

Without Monk and No. 3 receiver Virgil Seay (sore hip), the Redskins have lost 41 receptions and almost all of their depth at that position.

Monk, one of the team's most important players, will be replaced on early downs by Garrett, the 5-foot-7 special teams star who has caught one pass in his two years with the Redskins.

On third-down passing situations--when Monk became the man in motion as the second tight end--Rick Walker and Nick Giaquinto likely will fill in. Backup receivers include tight ends Clint Didier and Rich Caster. Gibbs said earlier this week that Charlie Brown also could be used at Monk's flanker spot, with Garrett moving to Brown's split end position.

"I still think things have gone pretty smoothly this week," said Theismann, making his first playoff start. "I didn't see us missing too many beats in practice."

Theismann, in his ninth pro year, already has had what he calls "my most satisfying and gratifying" season. Now, he is being asked to produce points with a unit for which Brown is the only other healthy player at a skill position.

By being voted to the Pro Bowl and by winning the NFC passing title, Theismann finally has achieved the personal recognition he has craved for so long. But the Redskins feel they need an extended playoff run to gain that same respect.

"We are aware people don't fear us and don't give us the respect we deserve, but I don't think many guys are upset about it," said Theismann, who completed a career-high 64 percent of his passes for 2,033 yards this season, the fifth straight he has thrown for more than 2,000 yards. "The playoffs are where you really get known as a team. You get national exposure, which we haven't had this season."

The offense will try to avoid making the kind of mistakes that hinder the defense, one of the league's strongest. The Redskins would like to run consistently, but the Lions have the NFC's No. 1 rushing defense, although both middle linebacker Ken Fantetti (shoulder) and end Bubba Baker (leg) are injured. The Lions' secondary, which starts rookies Bobby Watkins and William Graham, has been much more vulnerable.

The Redskins remember a Detroit offense that gained 499 yards against them last year in a 33-31 loss to Washington. But the Lions haven't been very effective this season, even with Billy Sims gaining 639 yards.

They are 13th in the NFC in offense, one reason Coach Monte Clark changed quarterbacks this week. Eric Hipple, who passed for 282 yards against Washington last year (Theismann had 287), is replacing a less-mobile Gary Danielson.

Hipple will be working against a defense that, the last four weeks, has given up an average of 7.7 points and 222 yards, only 87 on the ground. Sims gained that many against the Redskins in 1981 on just two carries.

The Lions also could be without receiver Fred Scott (13 catches), who has a leg injury. He would be replaced by Tracy Porter. Tight end David Hill (22 catches) and Leonard Thompson (17) rank behind Sims (34) in receiving.

"Any time you've had to move things around like we did this week, you don't feel as comfortable as you'd like," said Gibbs, who has only 10 players with previous playoff experience. "I think we've adapted well, but with the short week, we've had to scramble. It hasn't been the most pleasant experience. I'm sure the Lions feel they can beat us; everyone probably does. We'll just have to see how things turn out Saturday."

Joe Bugel, Redskins' line coach, said Fred Dean will start for Mark May at offensive right guard . . . Cornerback Vernon Dean, whose knee locked at practice Thursday, ran yesterday and is expected to play today . . . Kick returner Mike Nelms is near 100 percent after missing last week with a thigh injury . . . Mark Moseley won last year's Detroit game with a late field goal.