The gray clouds of uncertainty that hang over Redskin Park opened yesterday on wide receiver Malcolm Barnwell and offensive guard R.C. Thielemann, two players who joined the Washington Redskins a little more than a month ago.

Barnwell, obtained from the Los Angeles Raiders for a second-round draft pick next year, called his five weeks as a little-used reserve "mind-boggling" and said he did indeed understand the Redskins' system and was ready to play in the last three games, but never did.

Meanwhile, Thielemann, obtained the same day as Barnwell, from the Atlanta Falcons for wide receiver Charlie Brown, may be injured more seriously than was first thought.

Thielemann was put on injured reserve for a minimum of four weeks Wednesday with a torn anterior cruciate ligament in his right knee, but he and the Redskins' medical staff indicated yesterday that he may require reconstructive surgery and be lost for the season.

And, to top things off, guess who isn't talking to reporters this week?

Quarterback Joe Theismann, who has thrown nine interceptions and just two touchdowns in four games, told the Redskins' public relations department that he wanted to concentrate on football, not interviews, this week.

Whether this will be a permanent situation is anyone's guess.

With Theismann not talking about Theismann, it was left to owner Jack Kent Cooke, a visitor to practice yesterday, to do the honors.

"Joe is disappointed in what he's done to date and I share his disappointment," Cooke said. "But I fully believe he will come back with a wonderful game Monday night (against St. Louis at RFK Stadium)."

Theismann's silence adds further intrigue to the strange case of the Redskins' passing game, which has been a major disappointment so far in this 1-3 season.

Before he came here, Barnwell was a steady, well-liked starter for the Raiders. He caught 45 passes last season for 851 yards (an 18.9-yard average), his best season of a four-year career.

He joined the Redskins late in preseason -- Aug. 26 -- but said at the time that he didn't expect to have to make "a lot of adjustments."

Apparently, he was wrong. He has had to learn an entirely new system, he said, a change from the Raiders' "line up and play" philosophy to the Redskins' "move around a lot" offense.

The Raiders, he said, use words to describe plays when calling signals; the Redskins use numbers. It might not sound all that different, but it is, he said.

And Barnwell also has had to adjust to life on the bench. He has not played a down in the last three Redskins games, and was used sparingly against Dallas, catching two passes for 15 yards.

"He's our fourth receiver," said Coach Joe Gibbs. "If we get to the fourth receiver (in a game), he plays. He's been ready to play . . . it's just a matter of whether he feels comfortable."

And that is a matter of some interpretation. Barnwell says he has "the system down very well." Yet receivers coach Charley Taylor says, "Anytime you change to a new team, it takes a while."

But does it take five weeks?

"You might be seeing more of Malcolm soon," said Taylor, his eyes dancing.

For Barnwell, 27, it's a trying time. "When you're not playing like this, you lose a little feel for the game," he said. "When you do get in, it kinda feels brand new. You end up losing a little knack that you normally have."

Barnwell and Gibbs met a week ago to discuss the situation.

"I told him I wasn't used to this, and he told me to be patient," Barnwell said. "I'm a patient guy . . . I'm pretty sure I'll play more, maybe even this week . . . But I've never not played a down in a game before."

Barnwell, who said he would be satisfied if he played a "couple series" against the Cardinals, never figured he would beat out Art Monk, whom he backs up. But he did expect the Redskins to play more of the three wide-receiver offense they opened with against Dallas.

"I would call myself a big-play guy and a steady ballplayer," Barnwell said. "I really don't know what role they want me to play here."

As if things weren't going badly enough, Barnwell missed a quarterback and receivers meeting Sept. 26 when he had car trouble on his way back to Redskin Park from his home in Midlothian, Va., near Richmond.

He said he didn't know if he was fined or not, and Gibbs refused to comment on the incident, except to say it had no bearing on Barnwell's invisibility in the Redskins offense.

"It's not that," Gibbs said. "He came in here last (of the four receivers), late, in the four-spot. We're evaluating everything he does to see where he fits in. Normally, the fourth receiver doesn't play a whole lot, and we've had no injuries."

Meanwhile, Taylor likened the Calvin Muhammad-Gary Clark playing-time situation to that of running backs John Riggins and George Rogers.

"Gary got hot at the end of the Chicago game," Taylor said. "He was making the catches. It's like George. When he gets hot, he plays more."

But, for now, the starters are Muhammad and Riggins.

Having only seven offensive linemen, without three-time Pro Bowl guard Thielemann, "bothers you," Gibbs said. Center Jeff Bostic is eligible to return off injured reserve Oct. 15, but, said Gibbs, "In no way am I rushing him back."

He added that Bostic would not start automatically, nor even play a lot at first.

Thielemann showed up in the locker room yesterday to open some mail and commiserate with teammates. He said he will begin rehabilitation next week, but sounded decidedly pessimistic about returning in four weeks.

"I don't know," he said. "They might have to go in there and tie it together."

And if that happens?

Said Thielemann: "My season is over."