While the rollout of this update is expected to take place over a number of months, we've already begun analyzing winners and losers from this change. So far, there's no clear pattern to the changes due to a number of obscuring factors, including the length of the rollout, the lack of official confirmation from Google, and the difficulty in clearly differentiating between Google updates. Our own Marcus Tober explains the difficulty in identifying any big changes just yet. http://bit.ly/1LP9x6Q
On the other hand, there is a constant variation of the algorithm, implementándoce changes almost every day, so hard to see that an update mark a major change.
Finally, remember that version 4.2 of Panda is running along the 4.1, the 4.0 and others at the same time so I do not see possibilities to notice a major change to this new version of Panda.
I think that Google intends to dilute these major changes in order to make it difficult for websites to know if they are or not penalized.
Meanwhile John Mueller has said it is technical problems. Technical issues? if you have technical problems after the massive amount of preliminary evidence is that there is something seriously wrong with the quality processes, strange things in Google. I do not believe it.
While maintaining uncertainty may implement whatever they want.