crobb305 - 12:34 pm on Oct 16, 2012 (gmt 0) [edited by: crobb305 at 12:41 pm (utc) on Oct 16, 2012]
maybe Penguin just makes your site more susceptible to Panda?
I've been thinking this same thing lately. After the initial Penguin on April 24, the hit my site took was moderate. My rankings really tanked after Panda hit 3 days later. I didn't realize exactly how much of my traffic loss coincided more with Panda than with Penguin, until I really started looking at the traffic logs (in fact, I didn't know there was a Panda that week -April 27-, until I read it on a timeline somewhere).
We had a Penguin refresh last week, but some may have to wait until the next Panda to see if rankings can be restored.
I have a feeling that Penguin computes something along the lines of a "SpamRank", that could really increase your site's susceptibility to Panda et al.
[edited by: crobb305 at 12:41 pm (utc) on Oct 16, 2012]