The Redskins have informed quarterback Joe Theismann, who will become a free agent in February, that they have decided not to negotiate a new contract until after this season, a move that has left Theismann subdued and his agent shocked.

"I think the Redskins, from a psychological standpoint, have made a horrendous mistake," said Ed Keating, Theismann's Cleveland-based representative. "Joe can tell you that this doesn't bother him until he is blue in the face, but it does. They know he is a very emotional person. It's left a deep scar that I don't know if he will ever get over."

Keating and Theismann wanted to have a new contract, effective beginning with the 1982 season, signed before the end of this training camp. But after a few rounds of preliminary negotiations, General Manager Bobby Beathard informed Keating that the club was calling off the talks.

"We were so far apart that it was obvious we wouldn't be able to reach an agreement for a long time," Beathard said. "We didn't want the talks to go on while the season was being played. We didn't want to have that kind of distraction for Joe. They asked me to give them an answer and I did. So we thought the best thing to do was to end things for now and start again after the season was over. Hundreds of other players in the NFL are playing under the same situation.

"I'm sorry if Ed is upset, but I know that Joe is such a competitor that he won't be affected on the field. He's had a great preseason, and I'm sure he'll continue to play well."

Theismann's current contract, which pays him $200,000 a year, ends in February. It does not have an option clause, which automatically makes him a free agent.

Although neither side would discuss specifics, Theismann and Keating said they are aware that Philadelphia quarterback Ron Jaworski just signed for $300,000 a year and that other quarterbacks, like Archie Manning and ex-Dolphin Bob Griese, are, or were, in the $400,000 range. Those highest salaries most likely served as a starting point for Theismann's proposal.

If he becomes a free agent, Theismann would be able to negotiate with other teams in the league. But before he could sign with anyone, he would have to present an offer sheet to the Redskins, who could either match the offer or receive compensation. Compensation for a player of Theismann's stature would be at least two first-round draft choices. Fewer than a handful of players, none of whom were stars, have moved to another club under this current free-agent setup.

"I personally think there are some loopholes in Joe's contract that could circumvent the present free-agent conditions of the players' association-league contract," Keating said. He would not be more specific, saying he did not want to "tip my hand and give it away to them."

Keating admitted the Redskins are not obligated to begin talks now, although, he said, "It is the history of the NFL and all team sports that, for key players, teams begin negotiations during the last year of the contract, which means now.

"We made them what I think is a competitive offer. It would not have made him the highest-paid quarterback in the league. It was open to negotiations. You expect to have all proposals nipped away bit by bit until an agreement is reached. But they didn't want to do any nipping at all.

"We made a proposal to them, they countered with a proposal that was almost embarrassing, and we then gave them another proposal. That's when they called things off. I'm very disappointed in their effort. It was less than professional. They didn't appear to be very prepared.

"I'm disappointed because I know Jack Kent Cooke personally. If he's calling the shots in all this, why not deal with him head to head? You can't blame Bobby if that's the situation."

The Redskins' decision has had an affect on Theismann. While his on-the-field performance has not suffered, he has not been his usual outgoing, enthusiastic self. While he has cooperated, as usual, with the normal heavy number of requests for interviews and the constant demands for autographs, he has been more serious, almost sullen at times. He smiles less frequently and seems highly preoccupied.

"I'm concerned, sure, but it's something I have to live with," Theismann said when asked about the contract situation. "Am I happy with management? There is no reason for me to be happy or unhappy. I have a contract with the team and I will fulfill it. It's their prerogative not to negotiate now. I've got a lot of things on my mind.

"If I had my druthers, I would like to have had the opportunity to discuss the issue, but I don't believe we've really had that chance. Beyond that, I want to let Ed Keating, Bobby Beathard and Mr. Cooke handle any questions about the contract. I don't have any other comment. I'm just going to concentrate on football and try to help make this a great year for the players, the system, the team and, most of all, the fans. There is no way I'm going to change as a player, I'm sure of that."

The contract stalemate comes at a time when Theismann has never been more delighted with his head coach and the offensive system.

"I can't wait to get the season going. This is like heaven," he said. "Joe Gibbs is fantastic. He's probably the greatest thing that has ever happened to me in my professional playing career. A quarterback couldn't ask for a better situation or a better offense.

"But the Redskins apparently want to test me to see if I'm strong enough to hold up in his system. I'm just going to concentrate on football and let everything else take care of itself."

Keating, however, wonders if Beathard and Cooke should risk having, as he put it, "the team's key player" in limbo during the upcoming season.

"I think once Joe steps over the white line into a game, this won't have a serious effect," said Keating. "But it will have a subconscious affect on him everywhere else, from practice on down. This will be disturbing to him and I can't believe management would let that happen.

"I told Bobby, 'I don't really know how well you know Joe Theismann. For what it's worth, you're going to have a psychological problem with him that you're bringing on yourself. He's an emotional, high-strung guy. He lets things bother him.'"Maybe I'll let things cool down for awhile and then approach the Redskins midway through the season to see we can get the talks started again."

Said Beathard: "Joe is having a great camp, so it's apparent his football approach is still 100 percent right. He told me he wouldn't be affected by off-the-field things and I take him at his word."