That Sean Hayes transforms in the new play “Good Night, Oscar,” there is no doubt. Whether the end result is a human being or a bag of tricks depends on your taste for ham.

GOOD NIGHT, OSCAR

One hour and 40 minutes with no intermission. At the Belasco Theatre, 111 W. 44th St.

In Doug Wright’s mostly unsatisfying dramedy, which opened Monday night on Broadway, the “Will & Grace” star takes on the role of Oscar Levant, the virtuoso piano player, “An American in Paris” actor and humorist who became popular — and controversial — during the early days of TV. 

A wittier precursor to the likes of Harvey Pekar on “Late Night With David Letterman,” Levant, who died in 1972, would appear on “Tonight Starring Jack Paar” and make unpredictable cracks about schizophrenia, pills he took, Hitler and plenty of other not family- or network-friendly topics before brilliantly tickling the ivories.

New York columnist Dorothy Kilgallen once said of Levant, “I think he’s said more funny things than any man of our time.” That’s a bold statement to make about a fella who most people today don’t remember. 

But Levant was, indeed, devilishly hilarious and whip smart. And so, Wright’s play is littered with so many punchlines they could be the main character’s first language.

What’s odd however is that, despite Levant’s insistence in the play that “I don’t write jokes in advance, I’m extempore,” the zingers come across animatronic and limp as delivered by Hayes.

You expect to laugh so much more than you do. The actor is, of course, a genius at delivering a shocking, pre-written one-liner seemingly out of thin air, as he proved on “Will & Grace.” 

But, unlike Levant, hyped-up Jack wasn’t a character burdened by facial tics that were the result of mental illness, booze and drugs, or a gravely voice that sounds like a shock jock Richard Nixon impression. 

As the tortured Oscar, the actor seems to be checking off a mountainous to-do list of personality and body traits while keeping largely unaware of the other actors around him, likely because of all the showy shtick he’s focused on. 

Thus, the frayed-wire quality of Levant is not conveyed. He’s Oscar the Grouch, OK, but reasonably harmless. Hayes is sporadically moving as details of Levant’s pain come to light, but we never meet this wicked firebrand we keep hearing so much about.

And on this day the funnyman should be especially on edge. Wright’s play imagines Jack Paar (Ben Rappaport) bringing the “Tonight” show to Burbank, California, in 1958 for a special event taping that will feature the reliably outrageous Levant. 

But to get the piano player to the studio, his wife, June (Emily Bergl), needs to sneak him out of a psychiatric hospital under the ruse that he’s going to his daughter’s graduation ceremony.

June is an intriguing character in that she clearly cares about Oscar, but only so much that she’ll risk his health and well-being to do a TV spot. Stoic Bergl and Hayes don’t have much chemistry, but the actress has her own unique “What’s in it for her?” draw. 

One of Levant’s concerned doctors, Alvin Finney (Marchánt Davis), comes along with a briefcase full of meds and there’s a celebrity-infatuated studio assistant Max Weinbaum (Alex Wyse), who buzzes around the green room. Eventually, we see Levant in action with Paar, which infuriates NBC honcho Bob Sarnoff (Peter Grosz). 

The antics all sound much more madcap than they are, when Wright’s play actually tends to waver between sad — sometimes poignantly so — and sleepy.

The only fireworks in director Lisa Peterson’s production go off during the climax.

Levant was a contemporary and friend of George Gershwin and became better known for playing Gershwin’s music than his own. His frustrating reliance on the then-dead “Porgy and Bess” composer — when he wanted his own compositions to shine — is brought up in awkward hallucination scenes with actor John Zdrojeski.

But near the end, Levant gets behind the piano and plays Gershwin’s “Rhapsody in Blue” on NBC. Hayes, a gifted piano player himself, does this in full view of the audience — and from memory. 

That thrilling moment — without mannerisms, words, other characters or exposition — is the only time Levant and “Good Night, Oscar” come to life.

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