Coach Joe Gibbs acknowledged today he is very concerned about the preseason performance of reserve quarterback Tom Flick, whose sputtering efforts in two exhibition games have left the Redskins on the brink of a major problem at that pivotal position.

At the same time, Gibbs praised the play of cornerback Vernon Dean, the No. 2 draft choice who was beaten for one touchdown pass in Saturday night's 28-13 exhibition loss to Tampa Bay and was involved in unsuccessful coverage on a handful of receptions.

But Gibbs admitted that, judging from the results of the first two exhibition games, his hopes of an overall improvement in the squad's depth this season might have been misplaced.

"Tom is not playing the way we expect him to play," said Gibbs, choosing his words carefully. "He has to work his way out of it.

"Last year, we were very comfortable with him and he had progressed. But this year, he's not playing well."

Asked if the Redskins were considering bringing in a veteran quarterback to compete against Flick as backup to Joe Theismann, Gibbs said:

"We like to solve our problems with the people we have. We've been working with Tom and Bob Holly (rookie from Princeton) and Chris Garrity (rookie from William and Mary)."

But it certainly wouldn't be surprising to see the Redskins sign another quarterback, as long as they think that move wouldn't destroy Flick's confidence. However, if Theismann was to be injured now, Flick hasn't shown he is able to replace him.

Team sources said the Redskins have attempted to let Flick work out of his slump without pointed interference from the coaches. But now it is likely Flick and the offensive coaches will sit down and talk.

What makes this situation more perplexing to the club is that, even with limited experience last year, Flick had shown enough to persuade Gibbs he had a promising future. Now all that could be changing.

Against Miami in the preseason opener, Flick was handicapped by a porous offensive line and so-so receiving en route to a statistically misleading 13-of-18, 137-yard effort.

Against Tampa Bay, however, Flick began the third period working behind the first-string offensive line and against several Buccaneer reserves. He was given excellent protection for the most part, but still couldn't get a first down until midway through the fourth period. By then, Tampa Bay had scored 28 straight points and wiped out a 13-0 halftime deficit.

Some of the Redskins' offensive problems in the last 30 minutes, when they gained only 89 yards, weren't Flick's fault. Halfback Wilbur Jackson damaged his bid for added playing time by fumbling on two consecutive possessions, limiting Washington to five plays in the third quarter.

Still, Flick was not sharp. He appeared to be pressing and hesitant in his passing, although he completed seven of 11 for 63 yards, with one interception. That interception was discouraging, though, because it came on a pass into the end zone that nullified the Redskins' only scoring threat that half.

Meanwhile, Tampa Bay reserve quarterback Jerry Golsteyn, who played for a minor league team last year, was shredding the Redskins' second unit defense, rolling up 216 yards and throwing three touchdown passes in the third quarter.

Those defenders had not played well against Miami either, leaving Gibbs to admit "we did so many poor things in the second half that it's obvious we are getting a real dropoff in our play when the regulars come out (on both offense and defense). We just disintegrate.

"It's discouraging because we are counting on playing a lot of these people and they haven't been playing the way we expected. I had hoped for better depth. We just have to get better."

But Gibbs maintained that one of those reserves, Dean, is not giving him reason to worry.

"To me, I see good things with Vernon," said Gibbs, who may have wanted to boost the rookie's confidence. "He had a touchdown pass thrown on him, but he came back and made two great plays. One play (an interception that was nullified by a penalty) is a play that you win games with. He was aggressive, he hits people.

"He's in a spot where you are going to get beat. But we like the way he is coming along."

Dean said he wasn't reacting to receivers' cuts "the way I should. But getting this kind of work is the only way I can get better. It takes time, it takes time. Like the touchdown. It was a perfectly thrown pass. I had no chance.

"With time and more experience, I'm sure I can get better. I have to improve my reads and reactions. And I didn't know any of their receivers, although they were all good."

It's essential to the Redskins' defense that Dean, who was drafted because of his hard hitting and his experience in man-to-man coverage, develops into a decent cornerback. He is projected to be a starter, probably next year, and a nickel back this season. For now, however, LeCharls McDaniel is the nickel back.

Gibbs was much happier this week with the play of the first-string defensive line, and especially with how a new passing-down formation worked against the Buccaneers.

The Redskins unveiled a 3-3-5 alignment -- the team calls it the "30 nickel" -- in which Larry Kubin became a blitzing linebacker on every play. Darryl Grant became a nose guard, flanked by ends Mike Clark and Dexter Manley. There were the usual five defensive backs and two other linebackers, Monte Coleman and Rich Milot.

"That concept allowed us to get pretty good pressure on the passer, much better than last week," Gibbs said. "It will become part of our regular scheme." Rookie Jeff Hayes, with two 50-yard-plus punts, also had two kickoff that weren't returned. "It's nice to see that ball go into the end zone and not be run out," Gibbs.

Among the Redskins hurt Saturday were Clark (sprained ankle), Nick Giaquinto (sprained ankle), Rickey Claitt (sprained knee), Manley (hip pointer) and Alvin Garrett (bruised arm).