Some are suspecting a massive Penguin update is about to hit, while others think it might be a Panda refresh and others think it is just Google's normal actions on link networks. It is almost impossible to tell without a confirmation from Google, for all we know, it can be all three or more.
Here are some recent chatter comments from the forums:
Regardless of the weather anywhere overall my lowest-ever page views at 45.7% of 2014 average with the UK at 37.4% however fortunately not as bad as Friday at 26.5%, what a mess.
i did a small analysis.. i used two of my sites and ranked purely with GSA and 10 articles scraped and smashed one was used. it got hit.
for my one another site i used 5 unique articles, spun with wordai, smashed as 1 articles with GSA.. it got hit but only 4-9 position drops.. not like first one..
so its getting clear that its penguin 3.0
Update: On May 20th we got confirmation from Google that this was an update to the Google Spam algorithm. And Google has also released a major update to the Panda algorithm today, which began rolling out today, May 20th.