Margo, as far as I could tell, the cast and staging was pretty much the same as the London production. The stage was largely bare with very few props and the text was stark and moody, as it is here. For me personally, it comes down to the cast. In London, the cast really clicked and were believable as a family in trouble. Here, they seem like a random group of people who just met for the first time. Only Margulies and Sisto seemed to have any ken of the text.
I guess it's like a mirage...With the right cast, it seemed so wonderful and thrilling, but with a weak cast (and major misdirection), it's a convoluted mess.
I love your idea of Judy Davis, though!