After six weeks of seeing his team make steady progress, Joe Gibbs was experiencing his first really low moments as a head coach yesterday while lamenting what he called the Redskins' discouraging, sometimes "really terrible," performance against Baltimore Saturday night.

"The game probably exposed some things about our team, some potential weaknesses that could really hurt us throughout the season," he said about Washington's 13-7 victory, its third straight of the preseason.

"We aren't operating at the level that we will have to be to compete against the good teams in this league. It's that simple. The week before, we played pretty good, we made some big plays. This time, we didn't. We needed someone to make a one-handed catch or a big run, and it didn't happen.

"This is definitely a setback. We did some sophomoric things out there. I thought we were making real progress as a smart team, but we regressed. We've been harping on playing intelligently and then this. It was terrible, very poor."

Even though the Redskins won, Gibbs is too much of a realist to ignore the 16 penalties, dropped passes and other botched plays that dominated the proceedings. The offense, which had been so impressive in rolling over Minnesota, could generate only two Mark Moseley field goals. It took Mike Nelms' 54-yard punt return for a touchdown in the third quarter to pull out the triumph.

If it hadn't been for another steady defensive performance, Baltimore probably would have won the game even without starting halfback Curtis Dickey, who was out with an injury. The Redskins certainly did their best to lose, dropping at least one touchdown pass at the goal line, having another Nelms punt return to the end zone called back because of a penalty and having to settle for a field goal after recovering a fumble at the Baltimore 11.

According to Gibbs, the game exposed those potential Redskin problems:

* Offensive line depth. "We lost one guy (guard Russ Grimm) and we had to go with someone (Lee Spivey) who had just joined the team. We can't absorb injuries very well along the line." Grimm twisted his ankle and is listed as "50-50" for the final preseason game at New England Sunday.

* Receiving consistency. "We were really disappointed in the receivers," Gibbs said. "Those guys had really started to come on and then they couldn't make the plays against Baltimore. We kept finding a way to mess up. Right now, I don't think they are as far along as they should be."

* Tight end. "They were just average Saturday." Gibbs has been critical of that position most of training camp. He has praised starter Don Warren but has worried about backup depth.

"We should have been called for a couple of more penalties that they didn't catch," Gibbs said. "We lined up twice in illegal formations and no one noticed." The previous week, the Redskins twice used 10 men in a kicking situation, but apparently corrected that problem Saturday.

"I guess you could say with all the injuries and all, we've had a chance to look a lot at our young people," Gibbs said. "But I hate to see us go backwards. Our offense just isn't performing like it should. We have to get better to be a better team, it's that simple."

Gibbs did have kind words for one offensive player, fullback Wilbur Jackson, who gained 66 yards on 10 carries in his bid for more playing time. "Wibur has been our most consistent back in these games," Gibbs said. "He is really running. And I thought Terry Metcalf had some good efforts on a couple of plays. We'd like to get Joe Washington isolated more in the open field, that's our fault we haven't done that."

At least Gibbs was delighted with the work of his defense, which has allowed only 30 points in three games, the best in the league during the preseason. The Redskins have forced nine turnovers and have given up only three touchdowns.

"The defense is playing very hard, it has been every week," Gibbs said. "A guy like Dave Butz, you can't say enough about him. He's manhandling people. He's emerging a real force. He's going to wind up being an all-pro the way he is going."

Baltimore, with big help from three Redskin penalties, appeared ready to overpower that defense on its first possession. The Colts drove 58 yards as rookie Randy McMillan dove over from the one for a touchdown. An interference penalty on strong safety Tony Peters at the six preceded the score.

The Redskins should have tied the game moments later when Nelms raced 59 yards into the end zone with a Mike Bragg punt. But fullback Rickey Claitt was called for pushing from behind on ex-Redskin Dallas Hickman, a Colt linebacker, to nullify the score.

When Peters forced rookie halfback Zachary Dixon to fumble at the Colt 11 later in the quarter, Washington again had a fine scoring opportunity. But Art Monk had a Joe Theismann pass go through his hands at the goal line and Moseley had to boot a 30-yard field goal. He added a 51-yarder in the second period as Baltimore led, 7-6, at the half.

Nelms won the game when he took a Bragg punt at his 46, raced through the first wave of Colt defenders, then benefited from the blocking of Metcalf, who slowed three Baltimore players, to dash for the touchdown.

The Colts' only other legitimate threat came as the game wound down. Quarterback Bert Jones, who had played from the start, was collared from behind by rookie end Dexter Manley. The officials called Manley for roughing the passer to give Baltimore good field position. Greg Landry replaced Jones.

When Landry faced a fourth-and-six at the Redskin 31, Jones returned to throw an incompletion under heavy pressure from a blitzing Rich Milot. Colt Coach Mike McCormack later explained that Jones was the only messenger he had left to bring in a play.

Jones, getting his first extensive work of the preseason, completed only 12 of 28 passes for 168 yards, but showed a lively arm. The Colts had a lot of trouble keeping the Redskin front line from pressuring him, which forced many of the incompletions.

Without Dickey, the Colt running game generated only 102 yards, which still was more than Washington's 98. Roger Carr had five receptions for 80 yards and McMillan added four catches and 39 rushing yards on 14 carries.

McCormack was pleased with the play of his defense, but agreed with Jones that the offensive timing was affected by his quarterback's lack of game work. "This was the third straight week we have lost because of our special teams," McCormack said.

The Redskins used Theismann at quarterback for about one-third of the game. He completed five of 16 passes for 37 yards in his first start since it was revealed he has had contract problems with the team. Mike Rae, making his first appearance for Washington, was much sharper, hitting on seven of nine throws for 46 yards.