Vince Rogusky has a mechanical engineering degree from Lehigh and is halfway toward a master's degree in business. He is 24, bright, outgoing and has a fine employment potential as a corporate executive.

But he has no desire to be sitting in a large office 10 years from now, feet on his desk, daydreaming about what life might have been like as a pro football player.

He wants to live that dream now.

He wants to play tight end for the Washington Redskins despite having played that position in fairly undistinguished fashion for only one year at Lehigh, a Division I-AA power which rarely produces legitimate pro prospects.

Rogusky came to Redskin Park last month for a free-agent tryout. Washington agreed to see him mainly as a favor to Kim McQuilkin, a former Redskins quarterback and Lehigh graduate. General Manager Bobby Beathard believed McQuilken's sales pitch enough to become momentarily excited about Rogusky's ability. Then he watched some Lehigh game films.

"I wasn't excited anymore," Beathard said. "Then Vince called me and I should have told him thanks, but no thanks. But as a favor to Kim, I said we'd have him down for a tryout. We already have enough tight ends and this guy really has never done very much."

Rogusky, who last played in 1980 and spent 1981 in graduate school, knew nothing of Beathard's reservations when he stepped off the plane at National Airport and headed toward Redskin Park.

"All I knew," he recalled later, "is this was the chance I wanted. I approached it positively. I guess I really didn't have any other choice."

Last year, before the start of training camp, the 28 National Football League clubs signed 637 free agents to contracts. As of June this year, 646 have agreed to terms, according to the NFL Players Association. No more than 100 are likely to survive final roster cuts in September.

Yet, despite the great odds, free agents continue to flood the market. Teams are besieged with letters and phone calls from athletes pleading for tryouts.

The free-agent market also is a serious business for the NFL. The Redskins, for example, have remained competitive lately only through the signing of talented free agents.

"Free agents are needed," said Beathard, whose opening-day 1981 roster included 20 former free agents. "There are more players out there than there are rounds in the draft, so a lot of talented people are left when the draft ends. If you underestimate the value of free agents, you are making a big, big mistake."

The majority of free agents comes from four categories:

* Players who finished their college eligibility the previous year, but were not selected in the draft.

* Players who previously had been signed by other teams, either as free agents or draft picks, and then released without making an active roster.

* Players who have been on active roster before being released and clearing waivers.

* Players who either opted to sign with the Canadian Football League and now want to join an NFL team or who have played out their options with an NFL club and are eligible to be signed, for compensation, with another team.

There also are free agents such as Rogusky, who have been out of football for a year or more and now are asking for a chance again.

And there are some players with no chance at all.

"You get the overweight, no-skill guys who for some reason think they can make it," Beathard said. "A guy will tell you he runs a 4.5 40 and it turns out he's 35 pounds overweight and runs a 5.0 if he is lucky. You have to go on instinct and weed out the ones you know are fakes and impostors. But you don't want to dismiss anyone if there might be some hope he can play. You never know where a good player will turn up."

That's why teams investigate tryout requests from many players. They check with college coaches and scouts, just to make sure they don't make an abrupt judgment they later might regret.

Many teams keep track of college seniors for three years or more after they use up their eligibility. The Redskins carefully record each signing and release, in order to know which players are available in case of emergency.Their scouts keep tabs on favorite athletes who might have been drafted or signed by teams before the Redskins. When one of these players becomes free, the red light flashes at Redskin Park.

There is good reason to be so thorough. Former undrafted free agents now in the NFL include Seattle quarterback Jim Zorn, Detroit quarterback Gary Danielson, Atlanta receiver Alfred Jackson, Atlanta cornerback Rolland Lawrence, Houston safety Vernon Perry, Buffalo linebacker Shane Nelson, Dallas tight end Jay Saldi, Dallas cornerback Everson Walls and Denver linebacker Bob Swenson.

In the days before his Redskins tryout, Rogusky had tried desperately to contact McQuilken in hopes he would provide some insight about what to expect.

"When I finished at Leihigh, no one drafted me and I wanted to play pro football," Rogusky said. "But by the time I got to some clubs, they already had signed everyone they wanted and I didn't get a tryout with anyone.I spent last year as a graduate assistant coach at Lehigh and I kept in shape, hoping I could get a tryout this year. That's when I thought of Kim. I figured he could help, and he did. But I never could find him again to have him fill me in about what to prepare myself for."

Rogusky certainly never anticipated the whirlwind that followed his arrival at Redskin Park. Ten minutes after meeting Beathard, he was on the artificial turf field, being run through standard agility and quickness tests used by Washington scouts.

"They really worked me and worked me," he said. "By the time it was over, I was dead tired. Everything happened so fast. I came down on this World War II surplus commuter plane and never did catch my breath after that. There were all these players and coaches watching me and a photographer taking pictures. It was quite a scene.

"I really wasn't in the best shape. I had been sick and my weight had dropped from 218 to 211. I told them that, at 6-2, I could carry 225 or so. I just hoped they believed me . . . My game films really didn't show much. I had started as a running back in college and then got hurt, nd then I was moved to tight end my senior year. I never was contacted by any scouts -- hardly anyone is at Lehigh. We don't have a big name for football. Still, I felt I had something to offer a pro team. I always was convinced of that."

When his tryout was finished, Rogusky was told to take a shower and then report to Beathard's office.

On the final day of the NFL draft this year, about 5 p.m., the scouts left the draft room at Redskin Park and started to make phone calls. Their goal: to convince as many undrafted college seniors as possible to sign as free agents with Washington.

No draft-eligible player can agree to be a free agent until the draft ends. At that point, all 28 teams begin a frantic scramble for the best remaining prospects. Some clubs have representatives stationed at players' homes. Others, like the Redskins, prefer to call first.

Long before the draft, Washington assembled a potential free-agent list of players it did not expect to be drafted. Redskins scouts kept in contact with them, reemphasizing the team's interest while trying to develop a friendly relationship that could be useful on signing day.

On this list were players who might be too short or too slow to have been considered top prospects. Sme might have been projected for different positions than they played in college. Others might have had subpar college careers or been used improperly in college (a passing quarterback in a wishbone offense, for example).

In some cases, the Redskins also will sign a player as a favor to a coach or school or to make sure there are enough athletes at certain positions during training camp drills.

Most free agents are asked to sign contracts calling for about $30,000 a year. The good ones will get a $3,500 signing bonus, with more incentives added for such things as making the team.

This off-season, the Redskins have signed 36 free agents, more than most teams but fewer than clubs such as Dallas and Seattle, which always invest heavily in the free-agent market. The Cowboys' philosophy is that free agents provide much-needed competition for their veteran athletes.

At the beginning of last season, only the New York Giants, with 20, had as many free agents on the roster as did the Redskins. Five of the Redskins' free agents start, including tackle George Starke, middle linebacker Neal Olkewicz and safety Mark Murphy.

"You can't always determine a prospect just in workouts," Beathard said. "We make drafting mistakes. A guy who is drafted gets into camp and looks awful. Another guy is signed as a free agent and comes to camp and looks great. The key is to not overlook anyone who might have even the slimmest of chances."

Thirty minutes into his workout with Rogusky, Beathard had his mind made up. Despite his poor game films and his inexperience, Beathard was going to sign him to a contract.

"He ran patterns after going in motion, in college, like our tight ends have to," Beathard said, "and he looks good doing it. He is a big, strong, well-built guy with good hands, andhe runs his patterns with the kind of quickness you are looking for. He has a quick break. He's worth a try. I wasn't going to sign him, but that was before I saw him."

Rogusky walked into Beathard's office, sat down and made small talk with the general manager. Suddenly, Beathard told him he was impressed with the tryout and offered him a contract. Rogusky, admittedly dazed, jumped at the chance. In 10 minutes, he was off to the airport.

"I still can't believe it all turned out so good," Rogusky said. "All the way home on the plane, I kept thinking, did this really happen to me?

"I was out looking for a job before the tryout. I'm going to leave my avenues open, but for now, making the Redskins is my top priority. I don't even know who my competition is or anything.The way things have gone, maybe the less I know, the better."