Before “Garden State” became the overnight Sundance sensation of 2004 — and thus immediately became the hip new thing for hipsters to hate — it was simply a small-scale film that moved audiences with a sense of sorrow and hope over what it means to grow up in suburban America. It became for this generation of 20-somethings a bittersweet fairy tale about existing in a permanent state of limbo — over-diagnosed, trapped in a pharmaceutical state, and cast adrift somewhere between the sanctuary of childhood and the anxiety of becoming an adult.

For fans of the writer and director Zach Braff, who is best known as a wacky surgical resident on the NBC series “Scrubs,” it was surprising to see how different Zach Braff the movie star was from Zach Braff the TV funnyman. Quiet, pensive, a bit distraught, and yearning for guidance, “Garden State” was earnest if a bit heavy on the coming-of-age clichés.

But it’s this sense of introspection that has been missing from Mr. Braff’s follow-up endeavors; it was visible only in spurts during last year’s “The Last Kiss,” and it’s all but absent from this, the resolutely dreadful third installment of the big-screen Zach Braff trilogy. (And let’s hope it is only a trilogy.)

It only takes a few moments to be taken aback by how bland and derivative “The Ex” is, how far it diverges from the creative spirit that even those who were irritated by “Garden State” at least had to respect. Perhaps its demise is due to Mr. Braff’s move from creative force to pure acting talent. At least “The Last Kiss” had the strong words of Paul Haggis’s script to hold it up; “The Ex” relies on the flat, stilted directing of Jesse Peretz (“The Chateau”) and the juvenile, frequently moronic script by David Guion and Michael Handelman (both first-timers) to give Mr. Braff something to do.

(A short aside: If he hopes to revive his career, Mr. Braff should consider sitting down to write another film rather than trusting his fate to such lackluster collaborators.)

Mr. Braff may play a convincing pre-adult, but his big-studio films rely far too heavily on the same emotional notes. There’s really only so much one actor can do with the concept of angst: “Garden State” — the angst of growing up; “The Last Kiss” — the angst of a self-absorbed, 29-year-old man who finds himself tied to his future and regretting it, and “The Ex” — the angst of that chauvinist-turned-father as his worries turn to providing for the wife who no longer wants to have sex with him and the child who comes second to his bland office life.

“The Ex” tells the story of a young couple, Tom (Mr. Braff) and Sofia (Amanda Peet), who find themselves parents to a son the very same day as Tom loses his job as a chef at a New York restaurant. Sizing up his options, Tom decides it’s time to abandon his dreams and take Sofia’s father (Charles Grodin) up on his offer to work at his Ohio advertising firm.

Needless to say, Middle America isn’t the haven Tom and Sofia expect. At his new job, Tom is immediately paired up with Chip Sanders (Jason Bateman), a handicapped mentor in a wheelchair who at one time dated Sofia and now has his sights set on reviving the old flame and bringing Tom’s perfect life crashing down. As tensions rise, Tom does all he can to thwart Chip’s advances toward his wife while trying to negotiate the office politics surrounding the company’s big tartar sauce account.

But it’s unfair to dress up this tattered shell of an idea and pretend it’s some suave bit of storytelling. To a persistent musical score of goofy clarinets, this haphazard comedy opens with an awkward scene of Tom and Sofia debating names for their child, then follows the pair as they move into a new neighborhood (“look at all the white people,” they marvel) and as Tom starts his new job and goes head-to-head with a “cripple.” In the film’s most awkward scene, Tom tosses Chip down a staircase, claiming he can walk. It’s meant as moment of levity, but as we watch the limp body plummet, it’s hard to see what’s funny.

Messrs. Grodin and Bateman get some chuckles as the so-happy-he’s-creepy owner of the ad agency and the no-holds-barred ex-boyfriend determined to get back into Sofia’s pants, respectively. But the more Mr. Braff smiles and skips along as the stereotypical, clutzy husband, and the more Ms. Peet gets worked up in an array of contrived bouts of anger, the more we grow tired of these competing clichés — a stream of jokes that miss their marks.

Put more simply: Here’s a big-budget, multimillion dollar 2007 comedy that’s relying solely on jokes about breast-feeding, the in-laws, and the handicapped. Is this the best we have to work with? Forget “Meet the Parents,” meet the Braff pack — they’re awful.