Those watching the controlled scrimmage against the Colts today saw the Redskins unveil a new starting backfield of fullback John Riggins and half-back Joe Washington. But by the time the scrimmage was over, they probably were just as interested in the progress of a lesser light, rookie receiver Charlie Brown.

Brown, the eighth-round draft choice from South Carolina State, teamed with another impressive prospect, free agent Virgil Seay, to give the Colt secondary fits.

Even though Baltimor won the scrimmage, 26-23, Redskin Coach Joe Gibbs was delighted with the performance of Brown, who took advantage of Art Monk's heel injury to become his team's biggest long-distance threat. Although Monk's injury is minor, he was held out of the workout.

"Charlie was just outstanding, that was pretty obvious," Gibbs said., =and I thought Virgil had a good day, too. They keep getting better and better. They are legitimate candidates to make this team."

Brown, who caught the winning touchdown pass in last week's rookie scrimmage against the Colts, made back-to-back dazzling receptions.

The first was a leaping grab (an excellent jumper, he is nicknamed "Swann" after Pittsburgh Steeler star Lynn Swann) of a Tom Flick pass for 35 yards. On the next play, he overcame interference by defender Frank Dark and somehow held onto the ball at the one while stretching and falling to the ground.

He made four catches for 87 yards during the passing portin of the workout and caught one pass for 15 yards during the full scrimmage.

"I feel more comfortable the more I get out there," said Brown, who consistently has impressed Gibbs since his first minicamp in May. "I'm getting more used to working against zone defenses and that helped today.

"I like to make the big catches and get people excited. When I get into games like this, I seem to stop making mistakes and perform better. I just want to keep it up."

Seay, who is only 5 feet 7 and 170 pounds, missed last week wtih a pulled leg muscle. But today, he darted through the Baltimore defense for five catches covering 72 yards in the passing drill.

"He may be small but he gets open a lot," Gibbs said. "He's maybe the fastest guy among our receivers. We need people to go deep and that's what he does well."

Seay was a 10th-round choice by Denver last yera out of Troy State in Alabama, where he once returned three punts for touchdowns in one game. He averaged 22.9 yards a catch in college.

With Ken Harrison and Zion McKenney injured, Brown and Seay are getting more time to show they can play in the NFL. Gibbs has indicated he will keep three or four wide receivers. Monk and Ricky Thompson appear to have two of the spots wrapped up.

Riggins and Washington were expected to become the starting backs, but today was the first clear indication that Gibbs is leaning in that direction.

Neither Riggins, back after quitting the team for a year, nor Washington, acquired in the offseason from the Colts, made much of an impression in the scrimmage. Riggins carried twice for 12 yards in his first appearance before a crowd since last summer. Washington had one two-yard gain and caught two passes.

Furrback Otis Wonsley, a free agent from Alcorn State who has been a pleasant surprise in camp, was much more efective. He caught three passes for 32 yards; on a 14-yarder he refused to be tackled despite shots by many in the Colt defense.

That effort was matched by two other fullbacks. Clarence Harmon took a short pass and turned it into a 18-yard gain and Wilbur Jackson had 16-yarder with a bit of nifty running.

Quarterbacks Joe Theismann and Tom Flick didn't have much success with their long passes, so they settled for short completions. Theismann hit on nine of 12 for 87 yards and Flick connected on six of 11 for 74.

Flick fared better in the passing segment. He got off to a rousing start by finding John McDaniel behind the secondary on his first throw. Theismann, after a sluggish beginning, gained accuracy as he warmed up.

But the Redskins couldn't generate much of a running game against the Colts. Nor could they do much to stop Baltimore's constant use of draws, traps and screen passes. The Redskins were burned consistently on those plays, which, Gibbs admitted, proved his team "still has some work to do."

"We also made some silly, stupid mistakes at important times, like penalties and missed assigments," he siad. "We've talked a lot about those things and we have to play smarter." h