Whoopi Goldberg is like a concentrate of magic that expands on contact with an audience.

Honed in the offbeat clubs, discovered in an off-off-Broadway theater by Mike Nichols, this young entertainer, female and black, is offering a one-woman show in Broadway's Lyceum Theater with prominent billing reading "Production Supervised by Mike Nichols."

Make no mistake: Whoopi Goldberg's ability to become other people is mesmerizing. Her language is scurrilous, the people she depicts are lowlifes, morons, junkies or dimwits. Yet she draws from her audience that sense of humanity that makes us all kin. She is working on several levels simultaneously. She illustrates an individual, then comments -- and at the same time observes our reactions. It is a unique, nimble performance. Her wide, mobile face grips you with her savvy intensity, and she has an uncanny ability to embrace the hundreds watching her.

Her first-act parade of characters (she writes all her own material) is absorbing, but the flagging second act prompts a question: What happened to the usually reliable, smart "Supervisor" Nichols?

In such programs, one expects what the musicals call "the 11 o'clock spot," the moment when a Beatrice Lillie provides the entertainment's high spot, when an Ethel Merman sings "Rose's Turn," when Anna and the King of Siam waltz to "Shall We Dance?"

I find it odd that Nichols would let down his prote'ge' by ignoring so simple a fact of theatricality.

The matter brings up the present role of stage directors, whose billing has become increasingly dominant. It's gotten to the point where one often finds the director's name and not the author's over a marquee.

It was Alfred Lunt who once remarked that the chief responsibility of staging is to see that the actors "speak up and don't bump into the furniture."

Not that Lunt didn't direct: operas for the Met, plays on Broadway in which he did not appear. But it was low-key, not an imposition on a script.

Not that there is a lack of directorial work of prime quality.

One such surely is John Malkovich's "Balm in Gilead," at off-Broadway's new Minetta Lane Theater. Lanford Wilson's 10-year-old drama, his first, has 28 characters -- drifters, junkies, dealers and drunks who float in and out of an all-night coffee shop. What slight story there is concerns a young woman from the sticks taking her first steps into this lonely underworld.

This not only is an exceptionally large cast for a 399-seat theater, but it is a rivetingly fine one, recalling the Gorki "Lower Depths" the Moscow Art Theater brought to New York some years ago. The detailing of characters, their overlapping, the superbly realized ebb and flow, the very lighting of the play's rhythms are unforgettable. This coproduction by Chicago's Steppenwolf Theater Ensemble and the Circle Repertory Company will be around at least another few weeks, and while it hardly fits the spirit of the season, it is a superb example of what noncommercial theater accomplishes.

Another is Lloyd Richards' staging of "Ma Rainey's Black Bottom," the August Wilson drama about a legendary blues singer's visit to a Chicago recording studio. So far, it is Broadway's major dramatic achievement this season.

Richards staged this last season at his Yale Repertory Theater, and since half the cast is from that earlier workout, the production benefited accordingly. Lloyd's direction allows the playwright his internal rhythms and, instead of fighting the playwright, seems to respect every one of Wilson's numerous strands, sometimes even to the detriment of our attention.

Another Mike Nichols offering has the same quality of respect for the author -- this time too much. David Rabe's "Hurlyburly," a bitter (and familiar) look at Hollywood standards, goes on and on and on for about 3 1/2 hours. After Rabe's publicized dust-up with Joseph Papp over a previous script, I suppose Nichols had to swear in blood that he wouldn't suggest any cuts. For all its fine casting, less would have been more.

Another example of how not to direct is reflected in the rapid closing of what might have seemed a natural -- Friml's operetta, "The Three Musketeers." For five weeks of rehearsals, the cast waited for director Tom O'Horgan to stage the many musical numbers. "It was five weeks of sheer waste watching O'Horgan's inability to pull things together," sighed one cast member.

Thereafter, book writer Mark Bramble was able to prevail on his "Barnum" director, Joe Layton, to postpone another assignment and get the musical on its feet with the humor and movement Bramble had envisioned. With previews under way, Equity rules restricted rehearsal hours the final week. Fifteen hours of rehearsal time wasn't enough; and after the critics scoffed, the show had a quick demise.

Speaking of the critics and getting back to "Whoopi Goldberg," I was confounded by their reaction to her language, which they accurately described as "filthy." But the words are the same that David Mamet uses so generously throughout "Glengarry Glenn Ross" and "American Buffalo," both of which the same critics praised for "the beauty of its street language."

Finally, note the small type used for the Kennedy Center-bound Royal Shakespeare Company's repertory offerings, "Much Ado About Nothing" and "Cyrano de Bergerac." They almost whisper, "Directed by Terry Hands." Nothing so becomes a man as modesty.