“Redbelt,” which arrives in theaters on Friday, is David Mamet’s 10th feature film as a director, and with the exception of parts of his first, 1987’s “House of Games,” all of them, however alluring they seemed upon release, now seem negligible. In fact, the sheer number of prestigious but stillborn fizzles and outright flops on Mr. Mamet’s film résumé is staggering. Even a partial list of the films he’s either directed or written is enough to stock a weekend film festival for masochists: “The Postman Always Rings Twice” (1981), “Things Change” (1988), “We’re No Angels” (1989), “The Spanish Prisoner” (1997), “Ronin” (1998), “Lansky” (1989), “State and Main” (2000), “Heist” (2001), “Edmund” (2005). How many of these films would have been made if not for Mr. Mamet’s great renown as a playwright?

Perhaps you loved his calculated but effective screenplays for “The Verdict” (1982), “The Untouchables” (1987), and “Glengarry Glen Ross” (1992). Or perhaps you’re just a Mamet fan, and you simply respond favorably to his familiar trademarks — characters whose knowing cynicism is expressed in staccato bursts of jazzy dialogue and disdain for old-fashioned story development.

To anyone not enamored with Mr. Mamet’s ongoing spiritual development, as expressed in his recent television and film work, “Redbelt” raises an obvious question: Has he lost his wits? The film is about the world of mixed martial arts, a subject gravid with possibilities. To the mainstream press, the mixed martial-arts culture seems to be inheriting the shrinking world of boxing — at least in non-Latin communities. Certainly, the sport enjoys a more upscale following: The frat-house crowd tunes in en masse for the big pay-per-view bouts, and last season on HBO’s “Entourage,” the boys dropped in to watch Ultimate Fighting Champion Chuck Liddell ground someone’s head into the canvas.

Also, at least so far in the sport’s evolution, the fighters themselves seem to have come from markedly different backgrounds than the great boxers of earlier decades. Most of the ones I’ve encountered — Quentin “Rampage” Jackson, Thiago Silva, Keith Jardine, Scott Smith, George St. Pierre, Roger Huerta, and Randy Couture, who at age 44 is regarded as MMA’s elder statesman — are more serious and better educated (nearly all of them spent some time in college) than nearly any boxers I’ve known. As Mr. Couture, who has a small role in “Redbelt,” told me recently, “David knows our world and our profession. He studied jujitsu himself, and he respects us and takes us seriously.”

Mr. Mamet is serious, all right. There’s scarcely a funny line in all of “Redbelt.” How much he respects MMA fighters, though, is open to debate. His protagonist, Mike Terry (played by Chiwetel Ejiofor), an instructor who runs a martial-arts school, is such a student of the samurai culture that he disdains commercial competition, which by definition means that Mr. Mamet’s respect for fighters such as Mr. Couture, who do compete professionally, is tempered. In fact, Mike Terry, as written by Mr. Mamet, is something of a prig. “I train people to prevail,” he says. “There is no situation you cannot turn to your advantage.”

If that’s true, the exception is the use of flat dialogue. Mr. Mamet’s respect for the martial arts seems to have put a clamp on his nasty wit. In fact, an interview with nearly any of the top MMA fighters will produce more scintillating conversation than Mr. Mamet allows their film counterparts.

Mike’s code of honor is never really explained to us, perhaps because his creator hasn’t fully thought it through. It appears to be an ethos taken out of cultural context, a Cuisinart of attitudes derived from Japanese action movies and old Hollywood melodramas. In a myth-mongering piece written for the New York Times on Sunday, Mr. Mamet listed numerous highbrow influences for his fight-movie vision, particularly Jules Dassin’s 1950 London-based noir about the wrestling world, “Night and the City,” and Akira Kurosawa’s “Seven Samurai.” I suspect his real inspirations are far less exotic.

Montgomery Clift’s Robert E. Lee Prewitt, in “From Here to Eternity,” didn’t want to box, but finally got pushed too far. “If man don’t go his own way,” he declared, memorably, “he’s nothin’.” Patrick Swayze’s MMA bouncer in “Road House” bones up with “The Portable Nietzsche” between brawls, and tells his acolytes, “Be nice — until it’s time not to be nice.” (A snappier line than anything Mr. Mamet has come up with for “Redbelt.”)

Does it really require a spoiler alert to warn the viewer of the direction “Redbelt” takes? After a series of absurdly complex plot twists involving an accidental shooting, greedy promoters, and con artists recycled from previous Mamet films, do you think Mike is going to make it out of this movie without a showdown? If you do, you’ve never switched on an old movie channel. The only essential difference in the climax of “Redbelt” is that Mr. Mamet can’t quite carry it off. Part of the reason is that MMA, with its incessant grappling, doesn’t lend itself to a movie camera in the way Eastern and Western boxing does. Mr. Mamet probably thinks he’s depicting integrity by avoiding a big “Rocky”-style ending, when in truth he’s again exposing his directorial inability to close the deal in a way that satisfies an audience.

Mr. Mamet seems to believe that “Redbelt” is saying something profound. “The punch line of drama,” the filmmaker wrote in the Times, “is ‘Isn’t life like that. …’ but its elder brother, tragedy, is the struggle of good against evil, of man against the gods. In tragedy, good and the gods, are proclaimed winners; in film noir, which is tragedy manqué, the gods still win, but good’s triumph gets an asterisk.” What does recycled melodrama get?

Really, Mr. Ejiofor’s jujitsu master seems to be an idealized projection of Mr. Mamet himself, and the scumbags, hangers-on, and predators who surround the sport are the director’s metaphors for the people with whom he must struggle to realize his artistic vision. But when the vision is as stylized and puerile as “Redbelt,” we can’t help but feel we’re caught in Mr. Mamet’s setup — the work of a man who has practiced the art of the con for so long he’s taken himself in.