1script - 3:54 pm on Jun 10, 2013 (gmt 0)
Re: evolution of this thread.
I have been checking here from time to time and always go to the last message posted for expediency. But it was quite illuminating to go back to the beginning of the thread to see how this all started.
One thing that sticks out is that Sgt_Kickaxe (the OP) hasn't posted here since Dec 24th, 2012. I wonder if he has a success story to tell by now.
Another thing is that it was originally thought that the update had targeted only individual pages. My own stats are inconclusive - I never had trophy KWs which I could look at to see any measurable drop. In my case most of the traffic drop came from the further reduction of the total amount of long tail KWs.
So, even though JohnMu's comments in the Google product forum imply that Panda 21.5 works like a penalty and if you noindex bad pages, you may help good pages, it looks like this does not really work in this case. If you noindex more pages, all you will end up with is less Bing traffic. Google traffic to other pages will not be affected. Panda 21.5 appears to be just an event in which the "good content" bar has been raised significantly and plenty of UGC, perhaps already borderline, fell below.
Sgt_Kickaxe's initial assessment that the update destroyed traffic to "medium quality" content appears to be correct, it's just that "medium quality" is the new "low quality". Given that there's still plenty of low quality content in SERPs, I think Google simply took an easy road and labeled much of UGC as "low quality". Since they've had ability to identify forums ("x" posts by "y" authors note in SERPs had existed since at least 2009), they probably decided to give the low quality (less text?) filter there more weight.
Images have been initially thought of as having played a part but I think it's more like the lack of text on the image pages that was important, not the images by themselves. Perhaps at least a part of this update was aimed at controlling the explosive growth of Pinterest and the other UGCs just became collateral damage? Perhaps it might even explain why that update was not announced. How's that for a conspiracy theory?
Anything else I missed comparing the initial response to the update to what we know/suspect now? It would be awesome if some of the early posters in this thread chimed in again!