Thanks for an interesting post. One point that you are not mentioning here is the old google PageRank algorithm and its many simulators. The idea behind these is the more times Google revisited your page the more confident it is about its content. So the conventional thinking was that an older page would outrank a page that has not been around for a while since Google is still not confident about its content. However, if you look at links as you say and in particular social sharing a page without any history could be outranking one that has been around for 10 years but this could only be temporary as long as the social sharing process is active. For example a couple of months after a blog post was forgotten and no longer attractive to social sharing or as identified in the “Mashable velocity graph” we could assume that Google will also downgrade a page? Anyway, it would be good to see some studies about a life time of a page on SERPS.