What's wrong with theories? Theories are the basis of scientifically solving a problem. The boards are here to post your thoughts so other people can expand on them. It doesn't really matter if you are right or not.
If you don't like the update threads, don't read them. You can see the title of the thread just as well as everyone else. YOU made the choice to click on the link.
Now, let's get back on topic:
It would also be interesting to see if there is a concensus from those sites that have lost traffic on..
1. Are they affiliate sites with many links to the affilate host.
2. Do they have satelite domains which they cross link/one way link with sites particularly on the same ip c-block.
3. Are the drop in serps keyword specific or site wide.
4. Are some inbound links on mass from single domains. For example, a great number links from a footer link on a major site.
5. Have changes been made to keyword density recently.
6. Is there a distinction in ranking between major and minor terms.
7. Has there been any PR changes or backward link changes.