1. The decline started about a week ago.
2. There had not been any changes in our digital marketing strategy. We have been building links in the same way since February 2012. The strategy had been to acquire PR3+ one way links with varying anchor text from a variety of link types (i.e. permanent one way links, contextual links & directory links). Anchor text varies from renters insurance, rental insurance, renters insurance quotes, renters insurance quote, renter insurance, buy renters insurance online, affordable rental insurance, etc. 'Renters insurance' links didn't exceed 40% of the backlink profile while rental insurance was the next closest in terms of volume at 20%.
3. The only paid links we have acquired were from directories but those paid links make up a very small amount of our links. Almost all of the links you see in Open Site Explorer were acquired from content relationships although OSE shows a very limited number of our links.
4. We determine a quality site as relevant in topic, PR3+ and does not link to questionable neighborhoods.
I would appreciate any insight you can provide as we thought we were staying within G's quality guidelines and now we have been (at least is appears) penalized.