by Frederick » 2016-02-14 16:46
Generally Google is just place your website where it should be according to the latest algorithm. 1 keyword fall does not mean you got penalized. Pena usually occurs for all keywords that fall rankings at once.
I have a client who was affected by this past July. and recovery took about 3-4 weeks. (1 is not only keywords, but 4 main keywords)
I also agree with Sam. you should diversify your anchor text and where it will build backlinks.
You should try to build links on high PageRank blogs that is not less than PR3. the higher, the better, and not just PR PR blog but the exact page.