That's the seo filter theory (it's Barry Lloyd, btw, not me
). I liked that idea because, if I were Google, I would have done it.
It may still be a combination. All I can say is that I am convinced that the 'normal' and 'Florida' result sets are completely different sets from the start, which means that it isn't an seo filter that's caused the disaster - at least not
only an seo filter.
It may be that an seo filter is applied to the Florida results, but I still don't think so. I see well optimized pages ranking in the top 10. Certainly the results have been updated in the -garbage serps (the 'normal' results) and it may be that GG was refering to that as being the other update. I think that either GG got it wrong or maybe you used a word that he didn't use, because whether the change is an seo filter, a Hilltop-like or LocalRank implementation, etc. it's a change and not an update.
At this point I am convinced that the two result sets (normal and Florida) are completely different sets that are derived in different ways. The normal set does not transpose into the Florida set. I'll put some of my studies on the web for you to judge for yourself. You'll see what I mean. It'll be a few hours before I can do it, but I'll post the URLs here when they are up.