Google Panda 2.5.2 released October 13th – Verified by Matt Cutts
Did you notice a drop in Google traffic around October 13th? Matt Cutts tweeted that there was a confirmed Panda release on the night of 10/13. This release is called Panda 2.5.2
Many people noticed their site take an even bigger dive, some didn't notice a change at all, and others noticed they appear to have a new penalty.
I'm not too sure what was updated in this version of Panda, but probably a polish of the 2.5 release.
Why do I have a traffic drop after Panda 2.5.2?
I have heard from many people that 2.5.2 seems to be more major than minor. People complain they lost 40-60% of their traffic overnight. They also say their sites are 100% pure original content, original images, original everything, and they are not sure why they were singled out. If you know your site is a good site, and you received a traffic drop from Panda 2.5.2 or any version of Panda, I would look at your backlinks. When Panda rolls out, it devalues sites it deems to be of low value. When a site is devalued, it's outbound links give out less or no SEO value. Your site could have dropped in rank and traffic because many of your inbound links were devalued.
Another thing is many webmasters are getting more careful about their links, especially since Panda has been released. They are doing anything they can to ensure they are within Google's quality guidelines. Many of your links could have also been turned into a nofollow. Nofollow in addition to devalued inbound links would definitely cause you a traffic drop.