http://www.johnchow.com/ Professional blogger. My guess about the latest drop is that he drew too much attention to himself from Google with his last publicity stunt, and they manually tweaked him for some reason. -Michael
The serps change all the time. I really doubt Google manually intervened. JC is a valuable resource and quite rightly should rank at the top. Google will know that.
I tried to understand why one of my site dropped a lot these days and i could not figure it out!Well, it may just be this case!