An encouraging story this summer was the unmitigated success of Bridesmaids, and the emergence of star and screenwriter Kristen Wiig.  Not because of any grand notion that Wiig and company burst through metaphorical doors on any “Boy’s Club,” or that the R-rated comedy was a bellwether for a wave of future female-centered comedies.

Bridesmaids was simply Wiig’s turn. In today’s Judd Apatow era of comedy, where improvisation is king, the hierarchy of experience and promotion is the same as the improv comedy troupes from coast to coast, where many of these talents get started. Groups like The Groundlings, which trained Wiig, and the Upright Citizen’s Brigade where Amy Poehler learned.

So far, Apatow alone has fostered, promoted and, in some cases, waved proudly goodbye to James Franco, Seth Rogen, Jason Segel, Jay Baruchel, and Jonah Hill. Wiig was deservedly next. The “Saturday Night Live” comedienne had been stealing scenes for years in Apatow-produced comedies, like Knocked Up and Walk Hard in 2007, Forgetting Sarah Marshall in 2008, and Adventureland in 2009.

Again, Bridesmaids was a largely improvisational ensemble, like the other comedies under Apatow’s watch. Only this time it was a ladder of funny females, including Maya Rudolph from “SNL,” Wendi McLendon-Covey of “Reno 911!”, and Ellie Kemper from “The Office.”

Then there was Melissa McCarthy, another Groundling who, let’s be honest, you may not have been aware of if you hadn’t watched “Gilmore Girls,” caught her new CBS sitcom “Mike and Molly” mid-channel surf, or suffered through Jennifer Lopez’s The Back-Up Plan. But she crushed her role in Bridesmaids, as the obnoxious Megan, aggressively going for every joke with enough energy that people were quickly talking about Melissa McCarthy.

She won a highly-contested Emmy for Outstanding Lead actress in “Mike and Molly,” she sold another series to CBS about a woman having a mid-life crisis, and she was the host of a well-received “Saturday Night Live” episode by October.

Which means McCarthy is “next” up to the plate to play an Apatow-produced lead, all though she’s striking out on her own first. Variety says New Line is enlisting hot director Tate Taylor (The Help) for Tammy, a spec script McCarthy co-wrote — with her husband, Ben Falcone — and the intention for her to play the movie’s eponymous lead. Falcone and Taylor are also former Groundlings, of course.

Tammy is the story of a down-on-her-luck “loser,” not unlike Wiig’s Annie, who loses her job at Hardee’s and discovers her husbands infidelity in the same day. So Tammy sets out on a road trip with her foul-mouthed grandmother Pearl (basically a septuagenarian Betty White).

Only that’s where they differ. Wiig’s script was innovative, reinventing the age-old bride rom-com with wit and long takes. But the leaked Tammy script treks through familiar road trip hijinks, maybe in hopes of improvising the rest? It’s flimsy, repetitive dialogue, especially for a movie about an odd couple cooped up in a Trans Am, and the R-rated humor is closer to New Line’s undercooked Hall Pass than the awkward sympathy of Bridesmaids. Though it’s conception reminds me of Due Date, where summer favorites Robert Downey Jr. and Zach Galifianakis (like 2011′s Taylor and McCarthy) were paired for a mediocre road trip.

Here’s hoping it’s an early draft. Luckily, McCarthy has other opportunities in development. She sold a movie pitch to Paramount with Bridesmaids co-writer Annie Mumolo, about a group of Mid-Western women led by McCarthy who plot to steal the Stanley Cup. McCarthy is starring opposite Jason Bateman in Identity Thief. Then she’ll return to the fold in Apatow’s This is Forty and an untitled McCarthy-centered, Apatow-produced project back at Universal with Bridesmaids director Paul Feig (and maybe Jon Hamm). After all, she is next.