Dymero - 1:17 pm on Jul 12, 2013 (gmt 0)
It has been suggested by several people - including Tedster a while back - that Google is at least experimenting with, if not actually incorporating, AI.
I think they're trying, but haven't quite gotten there yet. At the very least they're doing machine learning, which is different, and could explain the increase in work Matt is giving webmasters in terms of nofollows and disavows: creating data points for the machine to learn (but this could be entirely left field).
So during your visitor "downtime", do the visitors go somewhere else? Did some other site get created/changed/briefly more popular (possibly from a media mention or social media buzz)?
As far as I can tell it's an industry dip. There's just fewer people looking for products in our niche at the time. It's a consistent trend for the last three years. Why rankings seem to follow is the mystery here. If anything, mini- and affiliate sites in our niche have been knocked out to some extent, but this was a few weeks ago.