So what is Penguin first?
On April 24, 2012, Google announced "Another Step to Reward High Quality Sites", an algorithm change aimed at fighting against webspam. The algorithm change was first called "The Webspam Algorithm" but eventually began to go by the name of "Penguin". This algorithm severely affected sites that had widespread keyword stuffing and participation in link schemes.
Client came to me with "Domain" which was obviously penalized by Penguine. And that was the problem i was to solve
To understand it was Penguin i looked the ranking history of several high frequently asked keywords, on which domain was ever in top. 2 of them were seriously penalized.
At the time I was looking for 3 possible problems:
1. Duplicated content made by competitors
I checked the SERP for whole phrases and nothing was found - no duplicated content
2. Google changes whole algorithm for the niche
Competitors were still in top and keyword density with other off-page params were almost the same
Penalty was near the date of Penguin update when keywords went out from 100. Its clear that if only part of website was penalized than we can't say the problem is about the whole "Domain". It was definitely Penguin
How to recover from it? Penguin is algorithm and it counts the appropriate outbound params for making decision. I Looked ahrefs.com stats for the pages with penalized keywords. Too many unnatural links with the same anchor list detected. There are 2 ways to escape from it: build more links with other anchors or to disavow links in webmaster tool.
I chose the both.
Anchor list was mixed with brandname to make 50% of the whole number, used pointless words like "company", "website", "here" and so on. It was about 70% of the whole. Some good relevant press-releases written with theese anchors and were published in relevant resourses. All links were enforced by bot clicking.
At the same time i disavowed several not valuable links and stopped paying for temporary links a bit later.
Also I used to write some relevant posts in social media and got alive transfers from it to the penalized pages.
All the works were made in 2 months period. After next Penguine update problem was fixed.
The solution is not cheap really but it was worth the business. The best way to be more accurate in getting anchor list and promote the website with very slow and proven tactics. Recovering is highload and expensive thing!