Google recently announced via Twitter that a new update of its basic algorithm will be released. The traffic, as reported, will be done today. In the announcement, Google also emphasized that, like most updates of this type, it is likely to have no obvious results because changes are mainly to improve search.
More generally, improvements to this type of updates, relate to how Google perceives search, different pages, and a combination of them.
For the time being, there is no mention of using the popular Penguin algorithm in the upcoming update. Last March, Gary Illyes, when asked, said there was a specific team working to optimize the Penguin algorithm. Of course this does not pretend that the algorithm will be included in the June update. It could well be a simple statement about its evolution and nothing else.
Now there is nothing left except to wait for the update. The question of many is how to update and whether something needs to be done by users.
Google has officially announced that there is nothing to fix. Updates sometimes take up to ten days to run. Also, it is important not to forget that this is a basic algorithm update, not just for a site quality update. Google updates are usually relevant. Its quality website is of course important but not a primary goal. So if you are trying to understand why your site no longer has a good ranking, do not try to find something to fix. Instead, it might be helpful to ask yourself why your site may no longer be visible to Google.