Forum Moderators: Robert Charlton & goodroi
How about these possible contributing factors:
You have hundreds or even thousands of IBLs from pages on other sites, and now, some or many of those site's pages have gone supplemental (as many have recently), or even out of all of the indexes entirely, because of low individual PR. This in turn significantly reduces your IBL counts, and/or the PR value of those IBLs. In other words, your juice is gone because their juice is gone or significantly reduced.
G does a periodic supplemental index cleanup, and finally drops old inactive pages (more then 12 months in sups), and there is no replacement page on that site with your link. If you were ever getting any links/juice from those pages/sites, for whatever minimal value a link from a supplemental page may have provided, they are totally gone now.
On the other hand, lets say your SERPs get unexpectedly better. Maybe several pages/sites that link to yours now have much better PR, and/or have come out of supplemental status, so your PR is enhanced as well. This may be temporary, and SERPs may float up and down for weeks or more, since the other sites are all eventually experiencing the same "float" factors as above?
If and when some degree of stability eventually returns, it may largely depend on which sites are first in the re-ranking process, and which are last, in any particular major re-indexing and/or re-ranking cycle.
I know this is probably the basic definition of the so-called "Googledance", but with the recent changes in the way G handles supplementals, with many more low PR pages from many more sites being sent there for no other reason that low PR, and coming out of supplementals due to G "tweaks" in the thresholds for supplemental factors, perhaps it is now just more pronounced.
Just a question for consideration and comment.
