The most important valuation factor is traffic. The more traffic you
get the more you will see the value of your blog rise. The content is
important so that you can maximize your earnings for each
opportunity.
For example, if your blog value is $100 then you will only get paid
$100 for opportunities that match well with your content. If the match
isn't very good then the value for that particular opportunity may
drop to $20 or even lower.
The term Search Engine Rank on your Blog Info page actually is your
Google Page Rank. If it isn't up to date please let me know.