I wouldn't call it the best supporting performance of the year, but it was very effective, I can't deny that. It will be ironic though if after all the great performances Amy did over the years she finally gets her Oscar for a forced handjob scene. Sure, there were some other strong Amy moments in The Master, but that one clearly stands out.
A wife trying to establish her control over her husband is not a very original theme. But I've never seen it done so...literally. It is a very basic, animalistic scene. There is nothing erotic about it, there is no passion, no love. It's just a woman claiming her territory. Her man might have power over other people (especially other women), but she holds power over him. And of course she is also a fanatic follower of The Cause, but that's beside the point :)
A great job by Amy, very well done.
Grade change: 91--->92. The movie won't make any money, but a great performance and Oscar nomination provides a small grade bump anyway. If she wins, she'll go even higher :)
Amy Adams data sheet
Image: The Weinstein Company