What really is Penguin’s objective?
One major reason for the Penguin update is to prevent over-optimization of links in terms of anchor text. Their algorithm aims at valuating links from relevant sites rather than non-relevant sites. The objective is to discourage overuse of anchor text and emphasize on niche/content relevancy of linking sites. Reliance on anchor text is no longer a deciding factor when it comes to SERP.
Getting your dates right
However, before we get all ‘hyper’ about linking the first thing is to check the dates since you noticed a change in traffic. A drop or an improvement in traffic after April 24th is an indicator that you have been hit by Penguin in a negative or positive way. Changes before this could be a result of Google’s Panda 3.5 update.
Full article here: Tips To Recover And Survive Google Penguin Updates