Something IS going on. -950? For some pages but not for all.
I'd say Google just went -950 in reliability in my opinion. Too many changes at the same time, too many bad things happen at the Plex like someone said. AdSense glitches, -950 changes, spam sites still there, not rhyme or reason to SERPs.
Not sure why some pages go -950 while others don't. Some of my main keywords are still in effect while some of them are not to be found anymore. It was ok for a bout a week, eventhough I only got roughly 35% back of the original traffic, but now it down again.
Like someone said, too much time is going to keep up with GOOG, not enough time to maintain the site.