I'd be more convinced about Whiplash getting into best picture if the grosses were stronger; Dear White People, for example, is doing better business. Of course, Winter's Bone got in with a very small total gross. And you're certainly correct, the enthusiasm level for the film seems high.
If there's any way the film can compete for adapted rather than original, they ought to jump at it. Original is already quite stacked, with Birdman, Boyhood, Grand Budapest & (presumed) Foxcatcher...where adapted has nothing but Imitation Game that you'd bet rent money on.
I still think of Grand Budapest as typifying BJ's bird-in-hand rule: it's the greatest success so far from a guy who's knocked on the screenplay door multiple times. It has a base of potential nominations (screenplay, design, possibly costumes or score). And, by anecdote like Sabin's and other I've heard, it's more BELOVED than any previous Anderson effort. It of course could be forgotten if five films opening between now and Christmas turn out wowsers. But we have no way of knowing that.
And it's the fact that we don't know about that string of films that leaves everything very much up in the air. Last year, by now we had only American Hustle, Wolf of Wall Street and Saving Mr. Banks still behind the curtain -- and still they managed to confound expectation, rewrite the nominations slate at the last moment (Hustle by running the acting categories, Wolf by scoring so many glamour nominations, Mr. Banks by crapping out entirely). This year, we're still to see Interstellar, Into the Woods, Unbroken, Selma, A Most Violent Year, American Sniper and Big Eyes -- each one of them a potential race-changer or potentially nothing at all. (Plus, though we've seen initial reviews, we don't know what ultimate impact Inherent Vice or Top Five -- films at opposite ends of the spectrum -- will have.) That leaves the race, as far as I can see, truly undefined: a rarity when we're only six weeks from critics' awards. Deciding which of those unseen seven will count, and which can be dismissed, is strictly wild-guessing at this point. I see people at the other sites blithely touting some (Interstellar, Selma, Unbroken) and sneering at others (Big Eyes. A Most Violent Year), but all that indicates is their own prejudices.
As far as Gone Girl: I think it has more going for it than Dragon Tattoo. It's turned into a bigger hit than anyone expected, where Dragon Tattoo was -- considering the wild popularity of its source -- only so-so. And Gone Girl's got enough talk-about-it vibe (the whole "what does this say about marriage") to provide some content heft. I'd say it's more likely to be best picture-nominated than not.
Oh, and The Gambler: if it turns out to be good, I'll be exceedingly surprised, based on the original, which I remember feeling I endured as much as watched.