In a sport dominated by giants, they are gnats biting away at the concept that pro basketball has grown too big for the little man.

In a game where muscle is idolized they are the 98-pound weakings who toss quickness in the face of bulging bullies.

In a profession where experience is revered, they are infant prodigies who dare perform the blasphemy of being good and naive at the same time.

The darting dashing young guards who have invaded the National Basketball Association the past few seasons are even threatening to return the fun of the game, for Bob Cousy's sake, to the backcourt, where stuffing a basketball 50 different ways is not a basic requirement for residency.

It is becoming a liability to be old and a guard in the league these days. Half the backcourt starters have been pros no longer than four years and 12 are in their third year or less. Three of the best teams in basketball -- Philadelphia, Kansas City and Los Angeles -- have starting playmakers in either their rookie or second season and one playoff contender, Atlanta, doesn't have a guard with more than three years experience.

This youthful trend couldn't have come at a better time. With handchecking becoming as rare as hightop gym shoes, speed and finesse now are almost as important in the backcourt as rebounds and jumpers are in the front court.

"You could use your hands and body to slow these guys down before," said Bullet guard Tom Henderson, an old geezer in his fifth season. "Now you better have help inside from the big guys. Some nights I can keep up. But other nights, it's tough."

On those tough nights, Henderson must feel like a traffic cop trying to issue a ticket to a speeding car in the midst of the Monte Carlo Grand Prix.

Players like Atlanta's Eddie Johnson, Golden State's John Lucas. Los Angeles' Norm Nixon, Kansas City's Phil Ford and Philadelphia's Maurice Cheeks are plenty fast enough just jogging from basket to basket. But give them a ball and yell "fast break" and it's like the Roadrunner escaping from Wie E. Coyote.

"When we played Kansas City, we did a good job of containing Ford in a half-court game," said Bullet Coach Dick Motta, "but we let him get away for about three minutes and he ran off a bunch of fast breaks and beat us. Quickness can a such a great equalizer. You can just run by people and turn what seems like harmless situations into easy baskets."

The upper echelon of these infant guards already contains one bonafide, $800,000 superstar David Thompson, a Mr. All-World (Lloyd Free), an all-league defensive genius (Dennis Johnson), half of a potentially classy mile relay team team (Gus Williams and Lionel Hollins), enough sharp shooters (Brian Winters, Kevin Grevey, Ricky Sobers) to man a SWAT squad and even a kamikaze advocate (Ron Lee).

But these are the polished players who subscribe to the Wall Street Journal as likely as Sports Illustrated and who have been around the league long enough to rest easy at night even after losses.

The younger members of the brigade, the ones who still slap hands after baskets and can remember their college fight songs, emerge as more faseinating in regard to their potential and their uniqueness.

"All most of them need is experience," said Henderson. "Some of them are going to be superstars for years to come. Every time you look around, there is another guard popping up to make things harder for you."

Henderson hadn't even heard of Cheeks, a second-round pick from West Texas State, until a few months ago. But the performance of the rookie playmaker has helped keep the 76ers among the league's elite clubs, despite the loss of Free and George McGinnis.

Cheeks, who runs as if attached to a motor scooter, is so unselfish he won't shoot as much as his coaches would like. But why bother when a quick pass to Julius Erving is an even surer way of picking up two points? Cheeks has got that play down well enough to rank among the league leaders in assists -- a feat previous 76er playmakers couldn't master -- although playing only 26 minutes a game.

No one has had to prod Ford to fire up the basketball; indeed his college coach, Dean Smith, had to be careful not to instruct him too vehemently on any single point. "Otherwise," said Smith, "he would do that one thing and neglect everything else. That is how coachable he is."

There were questions about Ford's endurance prior to this season, but now the only question is: How good can he be? Coach Cotton Fitzsimmons handed Ford the basketball the first day of practice, told him "you are the leader, my coach on the floor" and the Kings haven't stopped winning since despite almost the same personnel as last year's 31-51 club.

Ford stands as the leading candidate for Rookie of the Year honors, an award dominated so thoroughly by the league's tall timbers that only two guards have gotten it in the last decade.

It didn't take much coaching genius for Fitzsimmons to turn to Ford, the best player in college basketball last year, but the Lakers' Jerry West had to be convinced a bit more vigorously to place his team in the hands of Nixon, the unheralded former Duquesne star.

Los Angeles had figured Maryland's Brad Davis as it new playmaker last season and didn't get around to selecting Nixon on the first round until Davis was secured. Davis now is playing in the minor leagues; Nixon is almost as valuable to West as Kareem Abdul-Jabbar.

"The thing about Nixon is that he can have a bad night and the next time we play he'll make things happen that you know he couldn't do if he didn't still have his confidence," said West, who knows how slow the Lakers are without Nixon and how horribly their fast break performs with him on the bench.

Although he was third in assists last season (and is third again this year, one place ahead of Ford), Nixon is obscrued by a team full of superstars and high salaries. He was never a factor in Rookie of the Year voting but still managed to emerge as perhaps West's favorite player.

"Who else can I yell at? West said with a laugh.

Another of the gnats (Ford, Cheeks and Nixon are all 6-foot-2), is Atlanta's Johnson, who leaves the playmaking to Armond Hill and concentrates on pulling out electrifying fullcourt dashes that are so stunning they quiet even his volatile coach, Hubie Brown.

"He may be the quickest in the league," said Henderson, if Ford isn't. "He's learning not to foul -- much. He's maturing. He goes really well to his right so you have to try to force him to his left."

When Johnson, Auburn's all-time leading scorer, learns to use both hands equally, he could well double last year's rookie output of 10.5 points. He's up to almost 16 points this season, not bad for someone selected in the third round of the 1977 draft (49th player chosen).

If Johnson represents the bridge between the playmakers and shooters among his peers, the Knicks' Ray Williams symbolizes the potential. He has the ability to turn even Ford into an outdated model, if only he could better control his lavish talents.

"I'm going to embarrass some people this year, that's the bottom line," said Williams before the season started. But in between slam dunks -- he and Dennis Johnson might be the best backcourt leapers in the game -- and soft jumpers, he had embarrassed himself with enough turnovers to lose his starting position.

"When he settles down, he's going to be a hell of a pro," said Henderson. "It's frightening to see how good he can be. All New York has to do is be patient for another year or two. You can see it now; he can run jump and shoot. Where do you improve on that?"

The same can be said for Chicago's Reggie Theus, who has the height of a forward (6-7) and the instincts of a guard. No other rookie is scoring as much as Theus (16 points a game) nor causing his coach as many headaches.

His out-of-control style inherited from his days at Nevada-Las Vegas, can be sensational one minute and outlandish the next. But there probably was no better physical speciman in the last draft. The rebuilding Bulls have turned over playmaking chores to him in hopes of turning that raw ability into wins.

While Williams and Theus struggle for identity, Otis Birdsong is warbling a gunner's tune in Kansas City. He wasted away his rookie season on the bench but now spends his days catching Ford's passes and converting them into bull's-eye baskets.

His flight to stardom has been swift; there are few better shooters in the league this season. And at 6-4 and very hungry, Birdsong's future is soaring alone with the Kings.

"All I know is that we go to Otis in the pressure situations and he doesn't miss," said Fitzsimmons. "If pressure bothers him, he doesn't show it. Every team needs a shooter like him and he's just starting to show how good he can be."

The kiddy korps also has great backup help: Ron Brewer of Portland, a powerful hustler with a nice outside touch; Butch Lee of Atlanta, a 6-foot marksman who needs more minutes to fully develop his all-star touch; John Long of Detroit, a second-round pick who isn't shy about shooting, speed catalyst Ron Lee of Phoenix and Ed Jordan of the Nets, who is known simply as "Fast" around Piscataway, N.J.

Despite this conglomeration of talent, however, Henderson is thankful for one small favor.

"I think the quickest guard around is Larry Wright," he said. "At least he's on my own team, so I only have to cover him in practice." CAPTION: Picture 1, 2, 3, 4, 5, 6, The younger guards are taking charge: Clockwise, from top left, Reg gie Theus of Chicago, Norm Nixon of Los Angeles, Ray Williams of New York, Ron Lee of Phoenix, Phil Ford of Kansas City and John Lucas of Golden State are among the best. Photos by Associated Press and United Press International; Illustration, no caption, artwork by Milton Clipper -- The Washington Post