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There are a lot of posts related to recent Google.com SERP changes.
What I noticed is probably important enough to be in a separate thread.
Some history... My website heavily uses dynamic URLs and as a SEO (it's probably 'blue hat') I publish random set of such links on each page. Such technics were employed even Google Products (former GBase) which showed "We recently found ..." list of recent user-generated queries (Google recently announced "restrict search results pages from Googlebot" and GBase became Google Products integrated to Google). Big sites such as eBay and Amazon use it ("top products", "on sale", etc - all are random dynamic links)
And now, SERP for a specific search for KEYWORD1 shows page containing this KEYWORD1 as an anchor text of linked page without showing linked page tightly related to KEYWORD1! And this linked page is indexed too.
In some cases it shows sitemap with "KEYWORD1 KEYWORD2" with a child page "KEYWORD1" which naturally looks opposite (I have link from KEYWORD1-PAGE to KEYWORD1-KEYWORD2-PAGE, and I don't have link in opposite direction).
Still roving search results, few times a day: sometimes it shows correct KEYWORD-PAGE, sometimes incorrect KEYWORD-[PARENT-PAGE-WITH-KEYWORD-LINK], and it is very unpredictable.
Looks like Google changed a lot of Sitelinks-related for SERPs.
Even homepage is not shown: instead, child pages linking to homepage with requested keywords.
I think you've zeroed in on at least part of the problem. Links and anchor text are both on-page and off-page factors. When they change randomly every time Google spiders, then the page's signals are kind of "twinkling" so it's not surpising to see some of the rankings shift around in response.
Yes, shift in ranking... I always expected rank 0 and random links was not a problem... some pages have tollbar rank 1 or 2, very rare keywords shown usually in top 10 of SERP (dynamic query in URL), and toolbar ranking is still the same - but different data centers show either top-10 or nothing. Looks like still 'dancing', but I need to mention that I was playing heavily with title and description changes during last two months so my mobservations are not truly trustful...
For another specific keyword my site was _sometimes_ #VeryLast (random number between 650 and 950, very end of last page of SERP), and sometimes #120 - #150, and rankings is 0 for the first result in SERP for this rare keyword. So that I am expecting that purely TermFrequency-InvertedDocumentFrequency or something like that will play significant role, and not just linking-related ranking. During two-three weeks competing site is still #3-#5, but competition is huge and I see well-known companies constantly after #200...
Yesssss, homepage (root domain) frequently disappears, and page with query parameters is shown insted... "frequently disappears" - probably I have to wait few weeks for data sync...
1. You cannot see up to date PageRank, even though Google calculates it regularly (to many decimal places) and uses it as one of several hundred factors when they compute rank.
2. You can see Toolbar PageRank, which Google tells us is a snapshot of the "real" PageRank. Google exports this data to their toolbar servers about four times a year.
3. Actual ranking is influenced by many, many factors. PageRank is one of the important ones, but notice that it is not dependent on any query terms or keywords. It's a measure of how well connected your pages are from the rest of the web. The query-dependent factors are many, as are historical factors related to your site and its backlinks.
Your final ranking on any given search is a mash-up of many factors, and that can even include factors such as the geographic location of the person doing the search, their personal search history, what browser they are using, time of day and day of week - it goes on and on.