I have a high traffic site (a WP Blog) of about 3 years standing with several hundred posts.
Until around 8 April I had numerous page 1 rankings on Google for quite a few reasonable traffic keywords.
I use no black hat tactics.
I use mainly article marketing, as well as social bookmarking and directory submissions and link services.
Currently I use a variety of article marketing type services - UAW, 1WayLinks, NeuroLinker, BacklinkSolutions, Web2Mayhem, ContentSpooling, etc.
I also use link services like MyWayLinks.
At around 8 April, my traffic suddenly plummeted from around 600 per day to around 100 per day, and has stayed at that level. Currently some of my page 1 rankings are now on page 7 and some I can't even find on Google at all.
This is a major, and sudden, unexplained drop.
Does anyone have any idea as to whether there was anything that may have caused this?