William H. Macy in Speed-the-Plow

If one needs any further convincing that one actor’s presence can change the dynamic — and even meaning — of a play one already knows, look no further than William H. Macy’s performance as Bobby Gould in Neil Pepe’s Broadway revival of David Mamet’s Speed-the-Plow, which is finishing up its run at the Barrymore Theatre. Macy’s world-weary gravitas adds an entirely new and welcome dimension to Mamet’s amorality tale of wheeling-and-dealing in Hollywood — and the result is now somewhat less funny but ultimately more truthful than any production of the work I’ve seen before.

Macy — who founded the Atlantic Theater Company with Mamet — has returned to the New York stage for the first time in nearly a decade to play Bobby after the sudden departure of star Jeremy Piven in December. (Prior to Macy’s arrival earlier this month, there were short runs by Jordan Lage and Norbert Leo Butz.) While this is his first go-round with the play (although his wife, Felicity Huffman, played the role of Karen in the original Broadway production), Macy is naturally and completely comfortable with those unique Mametian rhythms.

At 58, Macy is about 20 years older than the script may suggest — and much older than his Broadway predecessors — yet he makes the role fit him like the proverbial glove. Unlike with Piven, we believe the years of Hollywood gameplaying have truly taken their toll on Bobby, who has finally been named his studio’s head of production and found the fulfillment of that dream has lead him into a spiritual, almost existential crisis about his life’s purpose.

It’s no wonder, then, that he’s susceptible to the dubious charms and oh-so-practiced naivete of his temporary secretary Karen (Eiisabeth Moss, whose performance has grown considerably more assured), who convinces him to “greenlight” a film based on an artsy-fartsy novel about the effects of radiation — after they spend the night together.

That decision, however, has devastating consequences for Charlie Fox (Raul Esparza), Gould’s longtime friend and “colleague,” who is expecting him to recommend an action film Fox has secured with big-time star Doug Brown, who works for a rival studio. Watching the pair’s banter turn from the vaguely brotherly in Act One to downright terrifying in Act Three — as Charlie not only “watches” his dreams of fame and fortune slip from his hand but truly recognizes his place in the food chain — is mesmerizing.

Much of the credit for that final scene, and the production’s success in general, belongs to Esparza, who gives a triumphant, Tony Award-worthy performance as Charlie. Almost scarily manic at the show’s beginning (as if hopped up on cocaine) and later just plain scary, Esparza’s Charlie appears simultaneously too smart for Hollywood, yet still not street-smart enough to have made it to the big leagues. His rapier wit, keen insights, and physical bravado also make him a bit of a wild card, yet one understands Bobby’s need to keep him close at hand.

Indeed, if Esparza and Piven seemed at times a little like overgrown frat boys playing at being grown-ups, he and Macy are undeniably full-grown adults — facing the abyss and desperately trying not to fall in.