HEY DAD, THEY'RE at it again! Those nasty movie people are picking on sports, hitting at it with their tiny little fists, battering it with their puny sensibilities. Won't anyone make them stop?

No, no one will, because sports is too fat a target, too easy a shot for film people to ever give up on. They know that, used judiciously, sports is close to an ideal metaphor for much of the competitive lunacy of modern society. The problem is simply that it is too good a metaphor, too unsparing. Sports can show us more about ourselves than we generally care to know, so we have prevented it from telling us anything. At least, we have tried.

What brings these thoughts rumbling down the way Smokey Burgess used to rumble down the third base line after pop fouls is the latest of Hollywood's forays into the sports arena: "Slap Shot," starring Paul Newman as Reggie Dunlap, the aging coach of a decidely minor league hockey team, the Charlestown Chiefs.

On the surface, at least. "Slap Shot" is a goodly distance from the awe-struck hagiographies that passed for sports films when Hollywood felt America was too innocent for the Whole Truth.

Who could ever forget Lou Gehrig's weepy mom standing by her man in "Pride of the Yankees," or Pat O'Brien making all them inspirational speeches in "Knute Rockne, All American." Sports was Caesar's wife in those days, the purest of the pure, and not a hint of the cranky lunacy that is the reality of organized athletics was ever allowed to confront the public eye. Even today, the great success of "Rocky" shows the potent results of tapping into that aging vein of sports sentimentally.

Say what you like about "Slap Shot," it certainly isn't pure, especially in the language department. Not since Andy Warhol's moods most foul has language so strong appeared on the screen. But the outraged moans of parents have been all but drowned out by the noise of "Slap Shot's" creators busily congratulating themselves on how gutisily realistic and true-to-sports-life they've dared to be.

But the odd thing about all that "realistic" language is that it somehow manages to sound phony and unnatural, as if it came out of the players' mouths with quotation marks already neatly in place around it. And this is unfortunately typical of "Slap Shot's" realism in genearl and its fidelty to sports reality in particular, all of which turns out to be strictly on the surface.

The surface, unfortunately, is what we've gotten used to in sports films, even in recent years when, theoretically at least, more biting forays would have been acceptable. While fans of other genres luxuriated in "the new permissiveness," whatever that was, sports types got nonsense like "Grand Prix," with Toshiro Mifune easily getting the nod for Most Incomprehensible English Spoken On Screen By a Non-American, or spectacles like "Number One" with Charlton Heston totally unbelievable as an ace professional quarterback afflicted with terminal ennul.

Films have shown up before "Slap Shot" which have been acclaimed (ha ha) as hitting new peaks in sports realism, films like TV's "Brian's Song" or the more recent one of his first major roles. What passed for realism in both these situations, however, was nothing more than hokey sentimentality centering around the presumably edifying spectacle of An Athlete Dying Young. Here, as elsewhere, playing things straight was a temptation the filmmakers easily resisted.

One of the odd things about sports films is that for many years the only forceful, gitty ones come from Europe, most particularly England, things like "The Loneliness of the Long Distance Runner" and the classic "This Sporting Life." No one who has ever seen Richard Harris in total agony over th way the violence in his professional life as a rugby players worked toward destroying the goodness in his personal life will be able to regard professional sports with total equanimity again.

This is much too elegant for the makers of "Slap Shot," who, when all else falls them, as it often does, simply fall back on a kind of cinematic overkill, the laying on of razzle-dazzle comic and editing effects with a trowel until, as Pauline Kael so nicely put it, the film becomes "so grimly determined to ram entertainment down your throat that you feel like a Strasbourg goose."

This treatment of sports as no more than a convenient punching bag is especially sad because it makes us conscious of opportunities lost. "Slap Shot" does deal with the madness that is sport, but only around the edges. It is really only a pseudo-iconoclastic film, showing much too clearly - especially in a scene near the end when coach Dunlap makes a teary plea for the guys to go out an d play good old old-time hockey "like Toe Blake" - how awfully snugly the old wine fits into new bottles.

It's not as if films haven't been made which are more than cheap burlesques, which understand sports and use them with all the adroitness one could wish for. Almost exclusively, they have been the work of director Michael Ritchie, films like "Downhill Racer," "The Bad News Bears," and even "Smile," which even though ostensibly about a teen-age beauty pageant has more game savvy than "Slap Shot" could ever aspire to.

Ritchie's films succeed because Ritchie understands competition, what it means and what it does to people and competition, which "Slap Shot" just about ignores, is the essence of sport.

Though they are invariably very funny, there is a leanness, an almost amoral hardness to Ritchie's work to the way his coaches manipulate his athletes, to the way his athletes manipulate everyone, most of all themselves, toward that ultimate grail: winning. This type of drama, skillfully conveyed, can be a fascinating, gripping entertainment, but unfortunately it is the type of unforced entertainment that the people who made "Slap Shot" know nthing about.