Like the much-lauded “Birdman,” Barry Levinson’s adaptation of a Philip Roth novel—dismissed by most critics when it appeared in 2009 as one of the author’s lesser works—is about an over-the-hill actor who tries to revive his career, but there the comparison stops. While Alejandro Inarritu’s film is all cinematic flash and speed, Levinson’s lopes along on an energy level as low as that of its exhausted protagonist. And though it plays with the idea that Al Pacino’s Simon Axler, like Michael Keaton’s Riggon Thomson, might well be hallucinating at least some of his experiences, it’s far less surrealistic in tone.

Still, one has to be thankful that while distinctly less successful overall than “Birdman,” “The Humbling” offers Pacino an opportunity to escape the near self-parody of much of his recent work (a quality that reached a crescendo in the awful “Jack and Jill”) in favor of a character operating at a far lower volume. The script introduces Axler in his Broadway dressing room as he prepares to go onstage as Jacques in Shakespeare’s “As You Like It.” Reading lines as he watches himself in a mirror, he keeps inquiring of his image whether the delivery is believable. Then, as he walks to the stage he gets disoriented and finds himself locked out of the theatre and unable to get backstage for his entrance because the staff don’t recognize him. It all turns out to be a horrible dream, of course, but when Simon does make it to the boards he dives headlong into the orchestra pit.

That earns him a stay in a psychiatric clinic, where he talks to his fellow patients about how he’s lost his mojo as an actor. But one gets the feeling that admission is itself a performance, just as he’d asked the emergency room nurse whether she was convinced by his moans of pain. In a way it’s a testimony to how convincing Simon can be that one of his fellow patients, Sybil (Nina Arianda), approaches him with the request that he kill her husband, whom she accuses of molesting their daughter: after all, he’d once persuasively played a serial killer in a movie.

Sybil will continue to press her case when the two of them are released from the facility, coming to his wooded New England estate from time to time as he refuses her again and again. But she’s not his only visitor: there’s his agent Jerry (Charles Grodin), who arrives to offer either a hair-restoring commercial or a starring role in a Broadway production of “King Lear.” (One of the better jokes, even though it’s dated even now, has to do with people coming to see him expecting another fall, just as they patronized “Spider-Man: Turn on the Dark” for a similar reason. Of course, that show’s already closed.)

But all that is secondary to the surprise appearance of Pageen Stapleford (Greta Gerwig), the daughter of old theatre friends (Dan Hedaya and Dianne Wiest), who shows up to admit that as a girl she had a terrible crush on him. A teacher at a nearby college, she’s been in a lesbian relationship for years with Dean Trenner (Kyra Sedgwick), but they’ve had a rift, and now she’s looking for something a bit different. Simon is not difficult to seduce, despite Pageen’s domineering attitude and occasional visits not only from an extremely agitated Trenner but from Pageen’s horror-stricken parents and her one-time girlfriend, now a transgendered male (Billy Porter). The relationship is clearly not without its problems, and they come to a head when Simon fantasizes about their having a child just as he’s making his return to the stage as Lear. Let’s just say his pratfall-expecting audience get even more than they bargained for—maybe.

Pacino appears to be channeling a good deal of his own professional experience to pay the haggard, psychologically fragile Axler, and the result is certainly a courageous performance, with some inspired moments—like the sequence in a vet’s office when he’s given a horse tranquilizer for his wrenched back. And the Skype conversations he regularly has with Simon’s therapist Dr. Farr (played with amusing understatement by Dylan Baker) give him the opportunity for some wryly deadpan humor, too. Yet ultimately even his herculean effort can’t entirely sell the essential absurdity of Roth’s story (as adapted by veteran funnyman Buck Henry and Michal Zebede), even as he’s garnering laughs. The Simon-Pageen relationship feels more like a literary contrivance—which it is—than a plausible reality, and the same can be said of Sybil’s approach to Axler, which at one point is implied to be a hallucination but in the end seems actually to have happened. By the close one can’t help but conclude that the film hasn’t played fair, despite the obvious commitment of the game cast down the line and the work of Levinson and his crew (including cameraman Adam Jandrup), who were clearly working under severe time and budget constraints.

“The Humbling” is an uneven, hit-and-miss affair, but it represents a comeback for Pacino and, to some extent, for Levinson, whose last feature, the virtually unwatchable found-footage horror flick “The Bay,” suggested that he might have simply lost it. This small, strange little picture indicates that the work of both is still worth watching.