Liev Schreiber takes the stage in a thick accent and a thin mustache. In the new Broadway revival of David Mamet’s “Glengarry Glen Ross,” he plays Richard Roma – a salesman, and a good one. For a potential mark, the son of the Midwest has sweet poison. “What I’m saying, what is our life? It’s looking forward or it’s looking back.” For the other salesmen in his hypercompetitive office, he has tough love. “F– that s–, George. You’re a, hey, you had a bad month. You’re a good man, George.” And for anyone who gets in his way, he has a stream of insults culled from the thick dictionary of Mametspeak: “You idiot,” “You f–ing child,” and a few others that a sense of decorum prevents me from repeating.

Ricky Roma’s adventures in real estate put him at center stage in Mr. Mamet’s astonishing play, and Mr. Schreiber makes the most of the opportunity. Even from an actor from whom we are accustomed to seeing confident, carefully etched work (most recently, Henry V in Central Park), it is a mesmerizing performance. Whenever he is onstage, the shark pool of Mr. Mamet’s play flares to something like life.

Because in the world of Mr. Mamet’s dramas – taut, crude, and funny – a true-to-life picture is rarely to be found. The patter of Mametspeak sounds wonderfully authentic; actually it’s heightened and stylized, closer to verse than straightaway speech. From the lips of actors attuned to its jumpy rhythms, “Glengarry” rings as one of the most crackling plays in the language. (“American Buffalo,” another Mamet classic that narrowly missed a Broadway revival this season, is another.)

Mr. Schreiber has an easy grasp of this style, but the same cannot always be said of his co-stars at the Royale. As Mamet’s salesmen duel for a Cadillac, macho pride, and the security of their own jobs, director Joe Mantello sometimes finds an incisive, racing rhythm, sometimes misses it. The play’s potential for comedy and, more often, for pathos, isn’t always fulfilled. If you love Mamet’s play (and I love Mamet’s play), you may find yourself wishing that a work so extraordinary had found a production that consistently equalled it. Too often, ordinariness abounds.

“Glengarry” is an ensemble piece, but two characters stand at its center; the play has a bivalve heart. On one side, Roma, the young, hard-charging salesman on the make; on the other, Shelly “The Machine” Levene, the washed-up older man, the one driven to desperate measures by his losing streak. Mr. Schreiber pounds away all evening long, but his co-star Alan Alda frequently does not. It’s a weirdly disappointing turn from such a talented man. There’s no arguing with the comic gifts of Hawkeye Pierce; nor is there much question of his dramatic range, particularly after the wonderfully insidious performance he gave last year as a corrupt senator in “The Aviator.” But his take on Levene doesn’t satisfy.

Did he, I wonder, find his interpretation of the character, then choose a voice in which to play him, or the other way around? In the opening scene, a little symphony of rationalization in a tacky Chinese restaurant, Levene tries to convince the boss to give him another chance at the good sales leads. Mr. Mamet has a knack for shifting the supplicant’s tactics: now hectoring, now wheedling, now making nice. But Mr. Alda rarely strays from a weak, whiny desperation. Worse, he delivers Levene’s lines in an irritating nasal wheeze, like Willy Loman pumped full of helium. What happened to the rich, expressive voice that has served Mr. Alda so well for 30 years? He needs it here. (Coincidentally, Mr. Schreiber has also shed the bottom few octaves of his commanding voice, with much happier results: an inspired take on the ambitious, preening Roma.)

“We are the members of a dying breed,” says Roma of his fellow salesmen near the end of the play. Is that true? Twenty years after Mr. Mamet wrote the play, the opposite seems to be the case. In this age of viral marketing, the sales maxim “always be closing” has become something like a national creed. It’s uncomfortably easy to detect traces of his characters in the miscreants and sad sacks that populate the daily news.

There’s Dave Moss, the aggressive, mean-spirited salesman who will happily break the law to get what he deserves; or rather, bully someone else into doing it for him. Moss is played by Gordon Clapp, who brings plenty of force and fire to the role, but doesn’t find much else: His Moss probably couldn’t give away ice water in the Sahara, let alone sell real estate in Chicago. Moss’s schlubby sort-of partner George Aaronow is on a bad streak that seems to have begun at birth. Jeffrey Tambor gives a superb, nuanced performance: funny but not ridiculous, pathetic but still lively.

In his last Broadway performance, Frederick Weller was sensational as the redneck pitcher in “Take Me Out.” As the young manager here, he seems to be still looking for the right blend of callowness and authority. In a pair of smaller roles, Tom Wopat quakes effectively as Roma’s victimized client, and Jordan Lage finds sufficiently obnoxious ways to irritate the sales force as an overbearing cop.

Santo Loquasto provides two functional sets, a gaudy Chinese restaurant and the ramshackle office, which Kenneth Posner lights with lurid reds and bleak whites, respectively. All of this serves the play well. What the production misses are enough moments when Mr. Mamet’s language takes arresting hold of your attention. Few playwrights working today can approach his ability to find the joy and power in words.

The best moment in the show comes when Roma is working over a new client in the restaurant. Mr. Schreiber makes his speech an aria of misdirected appeals. As he weaves his verbal web, the effect grows spellbinding. “We’re not the same,” says Mr. Schreiber, with his palm facing up, toggling his first two fingers back and forth between the men. “We are not the same.” The audience, like Roma’s victim, falls into a perfect, rapt silence. Though only for a few moments, the show lets us revel in the very finest theatrical language – that is, David Mamet’s.