'The Rocker' (PG-13)(out of four)

As Dwight Schrute on the hit sitcom "The Office," Rainn Wilson regularly steals the show -- from no less than the likes of his television boss Steve Carrell. He's the fiery, take-it-all-too-seriously, no-holds-barred co-worker who sees every day as an opportunity to jump over his colleagues on his way up the corporate ladder.

He is the most indelible spirit of today's sharpest sitcom.

But as Robert Fishman -- or make that Fish -- in "The Rocker," he's not given the dialogue, the situational dynamics or the supporting players he needs to make the material sing.

We know this because it's another character in the film who is given the best lines, and just the right amount of screen time. And as Wilson tries his best to carry the weight of the entire film, it's the lesser-known Jason Sudeikis who disappears and reappears at just the right times, who steals the show from under Wilson's nose.

The comedy is based around a familiar archetype: The guy who simply won't grow up. While four weeks ago, it was Will Ferrell and John C. Reilly doing their best to play the part of bickering 6-year-olds in "Step Brother,” and two weeks ago it was Seth Rogen and James Franco playing grown-ups still who still act like pot-smoking college frat boys in "Pineapple Express."

Wilson plays Fish, an aging rocker who's doing his best not to still play the park of rock star, while trying to forget the pains of the past.

In an opening prologue, we see him at the height of his career. A drummer with an emerging rock band, the group is about to make it big when an agent visits his bandmates one night, and convinces them to ditch the awkwardly proportioned, sweat-drenched, less-than-marketable Fish.

They agree, and we flash forward some 20 years. Fish now appears to be an unsuccessful telemarketer. When he gets fired, he becomes desperate and moves in with his sister.

The plot thickens when one day he hears his nephew, Matt (Josh Gad), practicing with his band downstairs. They are auditioning new drummers, and Fish hears the subpar auditions.

He tells Matt and his teen angst bandmates that he is the answer to their prayers, and soon enough a hit YouTube video has the amateur rockers talking to a manager from a record label -- David Marshall (Sudeikis), who promises to take them big-time.

As pure comedy, "The Rocker" seems to be more content with the little chuckles than the big guffaws, closer in tone to something like the quirkily emotional "Run Fatboy Run" from earlier this year, rather than the all-out audacious zingers of something like "Step Brothers."

For Wilson, and his fiery, physical style of humor, this poses a problem. He's funny on "The Office," because he's both trying to tap into, and suppress, his inner Ferrell -- always teetering on the verge of exploding, before hilariously boiling over.

But in "The Rocker," he's held back by a timid script. The movie wants to show him as the partying-obsessed uncle who freaks out his more mild-mannered nephew, but then it doesn't have any idea about how to creatively show him trashing a hotel room. It wants to be a story about musicians bonding with one another and rising to the top, but there's almost no emotional link between Fish and his fellow performers, half his age.

Really, it's Sudeikis who steals the show, popping up as the rapid-fire, vile-and-vulgar, flash-in-the-pan agent. He's like a mild mannered Ari from "Entourage,” racing into the room with cell phone in hand, always looking to make a deal. He stands out just as Wilson does in "The Office,” because it seems like he's winging it, making it all up as he goes along.

Wilson, however, isn't afforded such freedom. He is forced to hit his marks and keep the story moving forward. He's giving a 100-mph performance in a movie with a 55-mph speed limit. I'm sure we'll see Wilson again on the big screen, in a role that doesn't make him run in place or carry a story on his shoulders alone. I'm already looking forward to that movie.