Don't be worried drall, just observe. Observation makes good science of things.
More observations from my site
~ crawling is non existent right now save for the index page.
~ google cache of the index page is outdated by a week.
~ My top content is still ranked well and getting search visitors, less important content is getting none and rankings are gone for those.
~ The site isn't banned or de-indexed.
Eliminating what makes no sense leaves what must be going on even if that too makes no sense.
Right now I think a good majority of websites are getting "cherry picked" in that their best content is returning in search like always but how many more pages are being ranked well depends on site SIZE. Auto generated content doesn't count towards site size right now.
It seems to be percentage based, if size is deemed on topic, related, quality enough your site may be entitled to x% more top ranked pages. Sites like WW that are full of such content get more longtail traffic but not as much as before because the % is smaller than before. Crappy sites or small sites get their "BASE" quota and nothing more, they've lost the most longtail traffic.
What bothers me about this, if it's true, is that mashup sites also get their quota and it comes at the expense of the sites they scrape.
Gone are the days of auto-generated top rankings and going with 500 thin sites vs one good one, a good thing.
Speculations - nothing more. Incoming links overpower anything, work on those (carefully, lower quality pages could start replacing your best stuff if a quota is in play), link out freely and consider doing it WITHOUT nofollow tags since those are Google only. Relying solely on Google, well, look at the mess that's created.