Yes, I made changes to a handful of pages only, mostly discussing new aspects of an old widget. All original, including some ideas that are my own.
One other thing, the pages have images and 65% of the traffic was coming from image search. They previously received 90% of their traffic from image search up until Google changed the layout of their image search engine. Do you think that Panda/Penguin alter image search results as well since this dried up too? The images are still in Google but down 5-6 pages instead of being up top.
I don't see images being the problem, the image traffic metrics didn't change except in reduction, but nobody has really discussed what Panda/Penguin does to image traffic if a page gets most of it's traffic that. I have however noticed that when a page gets a lot of traffic from image search it can do poorly in web serps and vice versa, as if you can only rank well in one at a time.
I'm grasping at straws as to what it is Google dislikes about these now so I will go ahead and return a couple of them to what they were.