As in Best Actress 2010, I'm a little surprised to see this field so berated -- I think it's a pretty good lineup.
As far as replacements go, Lesley Manville is a bit of a lead/support litmus test -- she's SO dominant throughout Another Year that you could easily make a case she's a lead. But she's also absent from good chunks of the movie, and not really its narrative focus, so you could also argue she's a supporting actress. Either way, a wonderful performance. I also thought Keira Knightley -- an actress I've never remotely cared for -- was surprisingly spot-on in a tricky role in Never Let Me Go.
Helena Bonham Carter had some delightful lines in The King's Speech ("I don't have a hubby, we don't pop..."), but her character was mostly an adjunct to the narrative. It was nice to see her in a real movie again, after mostly a decade of Harry Potter/Tim Burton coasting, but I never understood the individual raves from some quarters. I didn't think she had much of a part.
On the OTHER end of the spectrum, Hailee Steinfeld is one of the more egregious cases of category fraud we've seen this decade. But she was memorable in True Grit, possessing a sharp, spunky presence, and a keen sense of intelligence (here I'm referring to both character and actress). The performance did feel somewhat directed to me -- though it was certainly WELL-directed -- and wasn't quite up to the level of a Patty Duke or Anna Paquin tour-de-force, my personal barometer for evaluating whether or not an unproven child actor deserves an Oscar.
I think both Fighter women are absolutely excellent. As Mister Tee says, Amy Adams deserves credit for her change of pace role, but she deserves even MORE credit for so effortlessly abandoning the more innocent side of her persona and slipping so easily into this more hardened character. That porch scene with Christian Bale ("I drank too much...I wasted a lot of opportunities") is a great moment. And Melissa Leo is equally wonderful -- her character was brassy and annoying, but realistically so, and the actress offsets these less appealing aspects of the character by showing us that, deep down, Alice Ward does operate out of love for her children. (She also provided us with my favorite new insult: "You're an MTV girl.")
But though I was perfectly thrilled with Melissa Leo's win, I voted for Jacki Weaver, who I was so thrilled made it onto the list at all. True, her role isn't so dominant in the early portion of Animal Kingdom, but she uses these scenes to foreshadow her character's monstrous behavior near the film's end. (The way she kisses her sons on the lips, while delicately tossing off her favorite phrase of affection -- "sweetie" -- is so creepy, it isn't remotely surprising she eventually becomes Very Bad News.) I saw Animal Kingdom on opening day, before Weaver had much buzz, and I can remember the moment in the film's final reel -- when Smurf really takes her family's situation into her own hands -- when I started to think, this woman is terrific, SHE should be Oscar-nominated. It may be that "discovery" factor that makes me feel more personally attached to her, and so I choose her by a hair over the Fighter women.