elsewhen - 8:08 pm on Mar 3, 2011 (gmt 0)
it seems that the issue is with the interpretation of this:
In particular, itís important to note that low quality pages on one part of a site can impact the overall ranking of that site.
if google had complete confidence in their ability to guage page quality, then this would have been a page-by-page update, but the quote above indicates that google is looking at an overall profile and then applying that to an entire site. yes, they have to look at the quality of individual articles, but they don't seem to have the confidence in the algo to apply the down-weightings on a page-by-page basis.
my understanding of the ramifications of this is that a very-low quality article could rank well on nytimes (a site that was not flagged as low-quality), but a very high-quality article on a site flagged as low-quality would not be likely to rank.
yes, it is individual pages that need to be acted upon, but i am not convinced yet that the pages that lost the most traffic, or even the pages that lost the most ranking positions are the offending pages. ranking drops are not just about a particular site - they involve all those sites that rank near you. so a drop from 6th place to 11th place could be caused by exactly the same down-weighting as a ranking drop from 6th place to 7th place. in the first case, there were just a bunch of competing pages right behind the 6th position - and they were right there to move up into the vacuum created by your downweighting.
my sense is that google is really trying to guage quality... if we are to take their word for it, then the types of things they are downweightings are: