Who's to say that Google can't use a human touch? Why could they not hire a project team to look at URLs and make determinations to check automated systems against human judgement? Google's business plan calls for the best results, but doesn't specify that it will ONLY use automated methods.
I proposed that this was a human affected update in the Traffic Dropped thread. I stand by that assertion. The results are too random (spotty, actually) to have come solely from an automated process.