Joe Theismann says he is not playing as poorly as many of his critics believe, but admits he is fighting to avoid what he sees as a return to a bad habit of trying to force big plays.

"I did that in 1978, but then I stopped," he said. "Maybe the first two games (this season) I was trying to force the issue and make something out of nothing. Instead of trying to make an impossible 20-yard pass on third and 20, it would be better to settle for a 10-yarder to give the special teams better field position."

Theismann sat down this week and carefully evaluated his performance in the Redskins' first two games of 1981. He looked at his impressive statistics (599 yards passing) and the team's woeful point output (17) and drew some conclusions:

The process of learning Coach Joe Gibbs' offensive system is taking longer than he expected.

"It's not an overnight turnaround process," Theismann said. "I thought it would come along quicker than it has. We are all still thinking more than reacting naturally. Maybe I'm looking too deeply into the system instead of taking what is there on many plays."

He wishes the fans would try to be more patient, both with him and the team, and give the Redskins time to improve.

"I think the fans are reacting superficially," he said. "If they would just take a step back and see the situation we are in, they would be more understanding. They are the best and toughest fans in the country and, with Joe's arrival, they had high expectations about the offense. It'll come, we are going to get there, but how soon, I just don't know."

He doesn't feel, because of his position and his standing as a veteran, that he has a special role on the offense. Rather, he believes, if he becomes more consistent, he will provide the needed leadership through example.

"I can't lead through talking," he said. "If we make some big plays, if we get the job done, that will be leadership. That's what players respond to. It's a stability thing. If I don't make stupid mistakes, we'll move the ball consistently and score."

He isn't unduly worried about the pass protection being provided by his young offensive line, and he isn't shortening his stay in the pocket because he fears being sacked.

"I'm not shell-shocked," he said. "I think my protection has been really good. When you've thrown as many passes in two games as I have (96), you are going to get sacked and pressured. But I lift weights three times a week to prepare myself for getting hit. It's part of the territory."

He isn't bothered any more by the team's refusal to negotiate a new contract with him, and he does not think his play is being affected.

"It's more a distraction now to the fans," he said. "It's one of the loose ends that the organization decided not to tie up. The fans should ask management why they created this situation. It's not my fault it exists, no question about that."

There also is no question that Theismann has disappointed many within the Redskin organization who were hoping he could carry the team until the younger players matured. Still, only three offensive starters remain from those who played in last year's first game, the receiving corps is thin, the offensive line is the least experienced in the league and injuries have knocked out key players.

Theismann said he is struggling just as much as his teammates, even though he already has set single-game career marks for passes (48), completions (27) and yards (318). Only three other quarterbacks in the league have thrown for more yards this season, but the Redskins rank, with Cleveland, as the lowest scoring team.

"If you had told me I would pass for 599 yards the first two games, I would have said we'd score maybe 35 points or more," said Theismann, after two games that rank among the six best passing of his career. "We just seem to be taking one step forward and two steps backward all the time. Mistakes are killing us, they are forcing us into bad situations.

"There is a whole lot of room for improvement as far as my play is concerned, but I'm not irritated with myself. This is a collective effort and we are all in it together. One person can't determine how well the whole team functions.

"As we play more, I'll find out more about the guys I'm playing with and they'll find out about me. Then we'll eliminate the mistakes, the indecisions.

"For example, on three of the five interceptions I've thrown, I've started to pass, reloaded and passed again. That's indecision. Now it's a matter of getting so familiar with the system that I run the plays naturally and not think about them. When that happens, then I can concentrate better on avoiding sacks and throwing the ball away on purpose. But it's hard to think of those things when you are concentrating so hard on the offense.

"I'm not having problems reading defenses. That I'm sure of. It's more a matter of getting everyone on the same page so everyone is coordinated, so I know how everyone else will react to defensive changes. Until everyone reacts the same, there will be mistakes."

Theismann said he has not been particularly upset by the booing, but he acknowledged what he calls "the honeymoon we had during the exhibition season" is over.

"The fans and this team are like newlyweds," he said. "The honeymoon is over and we're settling down into marriage. Things have to be worked out; the initial excitement is over. But if we endure, good things will come of it. I'm convinced of that."

Fullback John Riggins may see spot duty Sunday in St. Louis. He was running decently on his bruised knee yesterday.