The high school three-letter athlete has almost gone the way of the dinosaur. In recent years, young athletes have begun specializing in one sport, hoping the extra hours will benefit them in their pursuit of a successful collegiate career and a chance at the megabucks in professional sports.

But Brian Howard, a senior at Rockville High School, is one of the very few athletes to make all-Met in football, basketball and baseball in one year. And, if it were possible, Howard would play and probably would make all-Met in a fourth sport.

"I just have to do something with my time," said the 5-foot-11, 170-pound Howard. "I'm aware many people don't play three sports any more and would rather stick with one or two.

"I guess I could have specialized in basketball or baseball, but then I wouldn't have had anything to do during football season. I don't like sitting around with nothing to do."

According to Tom Manuel, the Rockville baseball coach, Howard is one of those rare, gifted athletes who come along once in a lifetime.

"In my eight years here, I've never seen a young athlete like him," said Manuel. "He's very fluid at every sport and really works hard at improving.

"And he has that great attitude. We set standards we'd like our kids to attain. But Brian sets his own, and usually they're much higher than the ones we set. You tell him something once and he does it. I know if I needed a ping pong or badminton partner, I'd take Brian."

Right now, Howard is preoccupied with leading Rockville toward a Montgomery County baseball title and a berth in the Maryland State A playoffs. He is batting about .450, played near-perfect shortstop and has a 3-0 pitching mark, including a no-hitter against Paint Branch. Howard's most impressive statistic is that he hasn't struck out in three years.

"Not a bad person to have as a leadoff man, huh?" said Manuel, whose team is 8-1. "Everyone strikes out sometime. Not Brian. He's an outstanding hitter and always makes contact."

Howard hit .380 as a sophomore and last year finished at .500. He also won eight of 12 pitching decisions. He has fallen off in the long-ball department this season, hitting only one home run this year compared to five last season.

But the 17-year-old has been impressive enough to draw the raves of Joe Consoli, a scout with the Major League Scouting Bureau. Manuel quoted him as saying, "Brian looks to have the talent and movement required to play big-league baseball."

"A lot of other baseball scouts have inquired about Brian," said Manuel. "Regardless of which route he takes, his future looks very bright. He's just in a perfect position to be successful."

Howard, too, feels he can play big-league baseball, but right now he still has a soft spot in his heart for basketball.

"I played football because it was football season. But I love basketball.

I've put in more time working on my basketball and baseball skills and I want to go to college where I can play both," said Howard, who has narrowed his choices to Towson State and Georgia Tech.

"The coaches at Towson State and Georgia Tech said I could play both with no problem. I haven't made up my mind yet, but distance may be a factor. My family has yet to miss any of my games and Georgia Tech is a long way away."

That's good news to Billy Hunter, the Towson baseball coach who was a coach for the Baltimore Orioles and formerly managed the Texas Rangers. "We're very interested in him," said Hunter. "He's the type of kid who we'd like to build our program around. He could play both sports here with no problem at all.

"Our basketball coach (Vince Angotti) loves him. He can fit in as point guard right now," Hunter said. "He's such a good athlete and he could play both sports. His playing basketball wouldn't interfere with my program at all. He'd fit right in."

Howard has rewritten just about every record in the school's history. He threw for more than 2,000 yards and 21 touchdowns in football. He averaged in double figures each year in basketball, including a 22.1 mark last season, in leading the Rams to the State A finals in '80 and '81.

One reason Howard has been able to "major" in sports is that he has gotten good grades each year.

"I have about a 2.6 this semester.My parents made it clear that if my grades went down, I would have to give up sports," Howard said.

Because seasons overlap so much, Howard has very little time to relax. But that suits him just fine.

"I got a little break but I used it to visit schools," he said. "I didn't need any rest."

So what does Howard do for fun? "I practice sports," said Howard. "That's my social life."