From the get-go, “Little Willy,” now at the Ohio Theater, goes for the easy joke.

William Patrick Hitler, Adolf’s Irish-born nephew, was by all accounts a bit of a loser. He crapped out in Germany as a Volkswagen salesman, limped over to America to make anti-Nazi speeches to empty halls, and finally wound up living in obscurity on Long Island. But look to the title. Mark Kassen, playing William for maximum lumpishness, hits him – literally – below the belt.

Hannah Arendt may have been the one to describe the “banality of evil”; Mr. Kassen hammers the point home. In an overprocessed, carefully structured, totally yawn-worthy show, he paints his lead as a sort of Willy Loman with a genocidal uncle, a washed-up salesman destined to die unheralded and unknown. Every time another story brushes Willy’s periphery, whether a woman trying to save her son from the camps or Willy’s own sons vowing never to have children, Mr. Kassen shies away from its drama. Instead, he chooses to return again and again to Willy’s dull, blinkered efforts to capitalize on his dreaded last name.

Willy Hitler could certainly be good dramatic fodder: He was both excited and repelled by Adolf, bewitched by celebrity, and dropped names like Rudolf Hess as a party trick. Clearly, Mr. Kassen saw gold in those hills – today’s celebrity obsession isn’t so far from Willy’s own, and in interviews, Mr. Kassen talks about parallels with bin Laden’s niece, and her own search for fame.

But Mr. Kassen has only a thimbleful of content to spread over his hour and a half. Instead of either inventing new anecdotes from whole cloth or diving even further into the historical record, Mr. Kassen opts for constant repetition. Three times we return to Willy’s sales pitch for the VW Beetle. Three times we have to see him pick up women, and then fail to impress them in the bedroom. And three times Willy prays to heaven for the respect he feels he’s owed. By the time he discloses that the Fuhrer paid him to leave Germany, you kind of see where Adolf was coming from.

Roxanna Hope, playing the many women in Willy’s life, does a yeoman’s work. While Mr. Kassen yammers at us in an adopted Irish brogue, she slides easily between German and Eastern European accents. She lurks at the edge of the stage, looking prim and contained in Clint Ramos’s costumes, and yet she still looms over Mr. Kassen. He works harder than a hamster on a wheel, but she’s the only one who ever gets anywhere.

Director John Gould Rubin usually displays a surer hand than this – he treated this season’s “Trial by Water” with incredible verve and taste. Here, though, someone has advised Mr. Kassen poorly: while solidifying their structure and aiming for perfect clarity, Mr. Kassen and Mr. Rubin manage to squeeze out most of their subject matter’s juice.

Even the design seems bloodless – Mr. Ramos gives them a wooden floor (rather unnecessary in the Ohio’s beautiful hardwood expanse), a projection screen backdrop, and two transparent Lucite chairs. It could have served any of a dozen downtown shows. Worst of all, Egon Kirinic’s computer projections are uneven and often bludgeon the scene with meaning (eliciting an audible groan was the cross that morphed into a swastika). At the end, the display turned into a quick history lesson. Slides with information appeared, from Willy Hitler’s death date, to the fates of his three sons. Finally, we sat forward. Let’s just say that it’s never a good sign in a show when a Power-Point presentation casts your actor in the shade.

Until April 30 (66 Wooster Street, between Spring and Broome Streets, 212-279-4200).