luckystrike - 12:36 pm on Apr 5, 2013 (gmt 0)
I've experienced the last google panda/penguin first hand having been in the market since 2004 [and enjoying great rankings for my quality sites which now are in the doldrums]
Google present algorithms are just sleazy to say the least. You want the ultimate proof of that? My brother seeing that I was making a successful business tried to copy my business model and setup another site on my subject topic. Now, my brother doesn't know anything about SEO or the subject matter of my site and doesn't care much about copyright so he basically plagiarised other sites heavily to build his superficial site! There is nothing he's written at all there - nothing - and he's already abandoned the project for almost a year now (he didn't build a single link back to the site!) - unlike my flagship site which modestly I believe to be a very good resource on the subject with a monthly magazine and videos and all! [I've worked on it since 2004!]
Today I'm seeing his site ranking 3rd for a competitive term in the industry I'm in [while my site is probably in page 17 suffering the rage of google]. For my flagship site I didn't receive any notifications of manual penalties in google website but I didn't notice a drop in traffic in April 24 2012 - I think even the subsequent Panda affected me. After that my rankings continued to slip slowly but steadily over the subsequent months.