Ralph_Slate - 4:56 pm on Oct 5, 2012 (gmt 0)
Google obviously can't compare those metrics for dissimilar sites, so they are likely comparing what they believe to be similar sites or even similar pages. But who is to say that they are correct in their comparison?
Let's say that I have a site describing the history of widgets, and you have a site that displays the current market value of widgets. Similar, but not quite the same because with the latter you would consult it to look up a value whereas you would consult the former if you wanted to learn more about the widget.
Google might classify the two sites as equivalent and make one disappear from the search results because they say that it has better metrics than the other when in reality it is being used in a different way.
I can't believe that Google would be dumb enough to use site-wide metrics for comparison because some sites have various sub-sections - message forums, blogs, data, reviews, ecommerce, etc., and that would be a really bad comparison. It really only could be a page-to-page comparison, but again, how do they know the comparison is between equal competitors?