Why Melissa McCarthy?

There's so much talk these days (especially this side of her Emmy win) of Melissa McCarthy, the hefty sister-of-the-groom from "Bridesmaids," possibly getting in on the Best Supporting Actress race this awards season and I'm at a loss to really understand why.
-
I really quite like the film (its an irresistibly funny Apataw-brand comedy), but not only does Kristen Wiig give the most complete, subtly amusing and empathetic performance in the film, but the best supporting turn is given by Rose Byrne.
-
In "Bridesmaids," McCarthy plays Megan, essential a grotesque who burps and farts and waddles, hitting her gross-out high-point when she takes a dump in a sink at about the halfway mark. Sure, she gets the obligatory "Apataw" scene in the third-act (i.e. the pep talk), but when she's essentially delivering the same monologue that Russell Brand has, I don't think it should count - I'm truly baffled by the praise, make it stop!