It might have been the most unexpectedly revealing acceptance speech in Oscar history: “Did I really earn this?” Sandra Bullock asked, claiming her Best Actress prize for The Blind Side in 2010. “Or did I just wear you all down?” On its surface, the question was a sly, self-deprecating joke: the Austin-based actress had staged one of the more dogged awards campaigns in recent memory, turning up on countless talk shows, magazine covers, and red carpets in the run-up to Oscar night. But Bullock also seemed to be acknowledging, with surprising honesty, a two-decades-long crawl to the top, through disposable rom-coms, forgettable action-thrillers,  periodic triumphs, and occasional turkeys (the night before she won the Oscar, she also took home the Razzie for the year’s worst performance, in the odious All About Steve). More than any actress of her generation, Bullock turned herself into a star through sheer persistence. She seemed willing to try just about anything—and occasionally make a fool of herself—if it might command the attention of moviegoers. 

Yet listening to that acceptance speech, you could detect the lingering anxiety in Bullock’s voice, the worry that—even after besting such exalted competition as Helen Mirren and Meryl Streep—some might not regard her as a “real” actress. You also got the sense that whatever role she chose next, the decision would be fraught: Was she supposed to carry on playing the approachably sexy, lovably goofy girl next door—the bankable star of Miss Congeniality (2000)and Two Weeks Notice (2002)—even though those parts come fewer and farther between for a middle-aged actress? (Bullock turns 49 this month.) Or could she now take the leap into the grown-up realm populated by the likes of Streep and Charlize Theron—women who break down the traditional distinctions between “box office draw” and “serious performer”? 

Three and a half years later, and after a long hiatus during which she divorced her adulterous husband, adopted a son, and appeared in just one film (a supporting role in 2011’s Extremely Loud and Incredibly Close), Bullock is finally ready to address these questions. This summer, she’s turning up alongside Melissa McCarthy in The Heat, an action-comedy about bickering law enforcement officials. Like director Paul Feig’s previous effort, Bridesmaids, the film takes a genre that’s typically been the domain of men—in this case, the Lethal Weapon–style buddy-cop movie—and gives it a faintly feminist twist. At first glance, it’s exceptionally canny for Bullock to pair herself with McCarthy, the rising star of Bridesmaids and the CBS sitcom Mike and Molly. In a season overpopulated with boy-centric comic book blockbusters, I’d be shocked if The Heat didn’t emerge as a huge counterprogramming hit. Yet there’s something disappointing about watching Bullock play another clumsy fussbudget in a crassly commercial effort. Despite its charming performances and laugh-out-loud moments, The Heat leaves you wondering if Bullock is going to win the occasional battle to stay on top but falter in the larger war. 

Consider the film’s opening, which introduces Bullock’s Special Agent Sarah Ashburn leading a drug bust and then instantly induces a sense of déjà vu. Bossing around her male colleagues and gloating over her success, Ashburn is barely discernible from such Bullock characters as Gracie Hart in Miss Congeniality and Margaret Tate in The Proposal (2009)—she’s a tightly wound know-it-all whose ambition has sent potential boyfriends running for the hills. Part of the wonder of Bullock, of course, is that she’s so innately likable that, again and again, she has managed to upend this sexist conceit. Instead of relishing the comeuppance of an alpha female, we find ourselves protective of her characters—and rooting for them to bring some emotional balance into their lives. 

And at least in The Heat she’s not forced to do all the work and bring to life a stolid or coyly aloof co-star, like Keanu Reeves in Speed (1994) or Hugh Grant in Two Weeks Notice. Instead Bullock plays the straight woman to the gloriously uncontainable McCarthy’s Shannon Mullins, a braying Boston cop who doesn’t want Ashburn claiming jurisdiction in her case. In screwball comedy terms, McCarthy is the batty Irene Dunne to Bullock’s sternly disapproving Cary Grant; whether elbowing each other aside to be the first to enter an apartment building or tossing insults back and forth like water balloons (Mullins: “I was married for six years.” Ashburn: “Was he a hearing man?”), the two women generate an exuberant comic chemistry. Physically speaking, they create a charming visual contrast too—one tall and lean, one short and round—and you almost wish The Heat really would go the way of classic screwballs and have these two mismatched eccentrics fall blissfully in love.

Alas, therein lies the problem, for both The Heat and Bullock, as she navigates this post-Oscar phase of her career: there are no such risks taken here. Ashburn and Mullins race around Boston against the predictable objections of Ashburn’s sexist boss until (even more predictably) our feuding heroines finally set aside their differences and work as a team. There’s none of the nuanced character observation of Bridesmaids and certainly none of the zany tenderness to be found in a film like, say, There’s Something About Mary, just lots of f-bombs and random explosions of bloody violence, in the manner of such recent hit comedies as Pineapple Express and Ted. And while there’s nothing inherently wrong with an actress returning repeatedly to a well-honed persona—see the careers of Marilyn Monroe, Audrey Hepburn, and Julia Roberts, among others—it’s hard not to feel that this brand of deeply forgettable fare is beneath Bullock. 

Shouldn’t every major artist have the right to take the occasional paycheck gig? In theory, yes—but the practice is trickier, at least for Bullock. For years she was widely derided for her attempts at serious drama: recall her turns as a recovering alcoholic in 28 Days (2000) or as a wealthy housewife who needs a hug from her Mexican housekeeper in Crash (2004). The triumph of her performance in The Blind Side—a movie that otherwise traffics in broad melodrama and racial stereotyping—was that she managed to expand and reinvent her persona; her Leigh Anne Tuohy is a vulnerable study of a steely woman suddenly unsure of her hard-held views of the world. With The Heat, though, Bullock makes such an aggressive retreat to safe terrain that it feels like a capitulation. Having proved her critics wrong once, she now seems afraid that she’ll prove them right all over again if she strays outside her comfort zone. 

Then again, perhaps The Heat is just a hedge before she makes a much bigger bet. In October Bullock will turn up in Gravity, an outer-space epic from writer-director Alfonso Cuarón (Children of Men). If Internet reports are to be believed, she will be the only performer on-screen for long stretches. The hope is that this will offer her the same opportunity Cast Away offered Tom Hanks—a physical and emotional tour de force that shows viewers a whole new side of one of America’s most beloved stars. The fear, at least to judge by the teaser trailer, is that this will be one of those CGI spectacles, like last year’s Prometheus, that render its actors beside the point. Either way, The Heat, genial but ultimately minor, throws the stakes into stark relief: if she ever truly wants to chase that Oscar-night anxiety away, Sandra Bullock has to be willing once again to risk falling flat on her face.