I've got a couple of sites that took a Florida hit that exhibit the exact same symptoms as sandboxed sites. No duplicates* involved, but I've believed all along that it's in the number and types of links that were and are still lacking for the sites.
Even aside from those, which is purely anecdotal, there seem to be some kind of connections and correlations between this phenomenon and the Florida phenomenon.
* While there were no duplications, there *was* a problem with the site, being done in Dreamweaver with a template run through, with the pages being properly dealt with after the very page tops, which were all identical, including the header graphic linked to the homepage with the same anchor text throughout.
I've seen this same phenomenon many times since then, with many sites. This is not a sandbox issue, but it is a very real issue with many templated sites or pages with headers or page-tops all identical.