"Fast Break," a negligible but marginally entertaining sports comedy about a rags-to-riches college basket-ball team, is the sort of attraction that used to fill the bottom half of doublebills. When it's over, you don't feel disappointed, but you're still waiting for the main feature to begin.

Only the occasional verboten profanity seems to qualify "Fast Break" as a theatrical release instead of a minor made-for-television movie. Gabe Kaplan, as a rabid basketball fan who quits a secure job in New York to coach at an obscure Nevada university, might end up in some future sitcom, although "The White Shadow" is way out front. He also falls short of the exceptionally high standards set by actors who have recently played basketball coaches: Ken Howard in "The White Shadow," Cathy Lee Crosby in "Coach," G. D. Spradlin in "One on One" and Bruce Dern in "Drive, He Said."

Kaplan's appeal remains a trifle mysterious to me. His diffidence is presumably a defense mechanism for shyness, but his comic personality seems guarded. It's more fun to watch a self-dramatizing neurotic like David Brenner cheerlead the laughter at his own jokes.

Kaplan's diffidence is even more alienating on the screen. At times you get the impression Kaplan has nearly disappeared behind that dense black beard, no doubt concealing a very boyish countenance. Rande Heller, the actress cast as his wife, has such lean, sharply chiseled features and such a forceful technique that she invariably commands the eye o the camera. Kaplan isn't a commanding presence at home or on the court, although he evidently studied courtside movement under Al McGuire. If anything, he gives off nebbishy vibrations.

The new coacn turns around a feeble program overnight by importing four outstanding black players from the streets of New York. Complications are interjected by characterizing two of the recruits, Harold Sylvester and Mike Warren, as fugitives, and a third, Mavis Washington, as a slick female guard disguised as a guy.

The fourth player is Bernard King, the most spectacular performer on the court and a surprisingly loose, amusing presence off the court. He's an imposing athlete who seems relaxed in front of the camera. There's something distinctively funny about his ominous frowns wicked grins and smoothly loping stride.

In game situations the movie benefits from the fact that many skilled players seem to be on the floor. King is, of course, a pro star, and Sylvester, Warren and Washington were top college players at Tulane, UCLA and Cal-Riverside, respectively. Two other UCLA stalwarts Larry Farmer and (Word Illegible) Spillane, appear in monor roles, and a considerable amount of unidendfied talent flashes by on the opposing teams.

The filmmakers never come close to distilling the excitement and tension of an entire game into a sustained miniature draina of five or 10 minutes. The big game, implausibly set up when Kaplan cons a rival coach, Bert Remsen, into a sucker pet, is so much diversionary back-and-forth until the last-second winning shot Suspense is generated by extraneous, arbitary details rather than the inherent, intensifying rivalry of the game itself.

Kaplan's character encourages stupid, unsporting behavior from a marginal player and a sneaky team manager (nicely played by Richard Brestoff) that throws considerable doubt on his ethics as well as his ability. But Kaplan never projects enough regret about these follies, particularly to the boys who perpotrate them, to justify forgivenss.