This is how optimistic Lenny Wilkens has made the Seattle SuperSonics: In a late morning workout yesterday, Gus Williams actually was bold enough to challenge Fred Brown to a shooting contest.

That's like a jogger taking on Bill Rodgers in a marathon, but Williams made it close. He stayed in for 20 shots, all from medium range. But once they moved out to Downtown Brown's radar area, the best pure shooter in the NBA put a quick end to the proceedings.

"I took Fred to 20 shots," Williams said to teammate John Johnson. "Sure," Johnson said.

Basketball fans here also said claimed - he never speaks loudly - that despite the loss of center Marvin Webster, the SuperSonics would be a better team than the squad that lasted until the seventh game of the league championship round last June.

For shocked Seattle fans, who never expected Webster would trade in the Sonic green uniform for New York Knick green money, Wilkens' words were considered as accurate as a weather forcaster saying it wouldn't rain in the Pacific Northwest this winter.

But sure enough, predictions of the Sonics' demise were exaggerated. Instead of conceding Webster made them a contender last year, they are showing they might have turned Webster into a star because a highly talented supporting cast.

"There is no question we'd be a fine team with Marvin," Brown said. "But why can't we be a fine team without him? We've got the nucleus from last year's team, we've made some good additions and we are all a year older. Like Lenny says, we are quicker and deeper than last year."

Probably no one should have doubted Wilkens in the first place. This was the same coach who took over perhaps the worst team in basketball last December and pulled off the Miracle of the Northwest. Now he almost has Sonic fans saying "Marvin who?"

Webster's departure couldn't have come at a more inopportune time for the franchise. The Sonics were about to launch a season ticket campaign for their first year in the massive Kindome, figuring they'd rack up impressive totals riding the crest of their playoff showing, when Webster announced he had signed with the Knicks.

So much for the ticket promotion. At first, sales actually decreased when 50 patrons turned in their season tickets, and all Seattle was pointing fingers at Webster once the city's reigning sports hero.

During the summer, Webster maintained he wanted to stay with the Sonics, who had taken him in a trade with Denver a year before when the word was out around the league that his poor health would never allow him to be a top-notch pro center.

But snags over how his new $600,000 contract would be distributed annually and a disagreement ove a no-trade clause resulted in Webster's exodus.

Seattle owner Sam Schulman, who offered more money to his star than anyone here expected he would, remains convinced that Webster's New York City agent, Larry Fleisher, never intended for Webster to wind up anyplace but the Big Apple.

Fleisher, as head of the league players' association, is trying to take another big bite out of the Sonics. He is heading a move to reduce the compensation the Knicks had to pay Seattle for Webster: $400,000, a first-round draft choice and Lonnie Shelton.

The Sonics could least afford to lose Shelton, the 6-8, 240-pound bionic, body who is responding to Wilkens' persuasive methods in the same manner as Webster did last season. He played so well that veteran Paul Silas is now the fifth forward, an indication of the depth on the Seattle roster.

Shelton always has had the raw talent to be an outstanding pro - he is quick, incredibly strong and a fine leaper - but he played too much at center and fouled too often when he was in New York to ever fully develop his skills.

Wilkens is using him as a reserve exclusively at forward and has been almost as valuable to the team as Brown, the most profilic backcourt sub in the NBA.

The Bullet coaching staff is convinced Shelton makes the Sonics a more formidable opponent, just because he is much more versatile than Webster even though he's three inches shorter.

"Marvin didn't score a whole lot of points off their set offense," Washington Coach Dick Motta said. "Shelton could be an offensive powerhouse once he gets untracked."

Shelton's presence has taken some of the pressure off the Sonics' other major front court addition - center Tom LaGarde, who was considered by many to be washed up after just one season at Denver.

LaGarde scored 32 points in a game last week. that prompted Wilkens to recite what one national magazine said about the former North Carolina star: "Seattle will be surprised about how bad LaGarde really is."

With biting sarcasm, Wilkens detailed his feeling about preseason predictions by sportwriters. "The least they could do is see the person and the team play first," he said.

The LaGarde suiting up for Seattle this season doesn't rsemble the awkward inconsistent Denver Nugget who was hampered by a slow recovery fro a knee operation.

"This LaGarde," said Wilkens "is the one who played in college. He's actually a better passer and quicker on offense than Marvin, and that allows us to be quicker as a team. He hasn't surprised me. I knew what he could do."

So did LaGarde, who cringed at stories about his ineffective rookie season.

"I needed a chance to prove I could be a good pro," he said. "There was pressure on me here and I still have a lot to learn. But this is an advantageous situation for me. Everyone is very helpful and I like the offense. I'm more comfortable in it every game."

It would be difficult to be uncomfortable surrounded by the likes of Brown, Williams, Dennis Johnson, and forward Jack Sikma, another young Sonic Wilkens patiently developed into a solid performer.

Indeed, with Sikma, LaGarde and Shelton, Seattle is the only club in the NBA that can match up with the Bullets' big front line of Elvin Hayes, Mitch Kupchak and Wes Onseld.

Without Webster, Wilkens has made some subtle changes. The Sonics bring the ball up the court faster and rely less on their set offense, and the defense can't depend entirely on funneling opponents down low where Webster once could stand and swat away shots.

Still, the Sonics led the league in defense entering this third week of the season and hardly were tested in their opening five games.

"You could see our improvement as soon as we began training camp," Wilkens said. "just being in the finals last year improved us. I think everyone is determined to try to get back to the finals again."

The Sonics certainly have rekindled the enthusiasm of their fans, so much so that 9,000 people bought tickets the day of a recent game against San Antonio. That swelled the attendance for the contest to more than 20,000.