A few years ago I had to create a new blog because of my blog host’s (Blog.com) poor performance. In the process I discovered something interesting.Your Alexa ranking is determined by your blog host and has little to do with your actual blog if they’re placing it as their sub-domain name.
If you have a host provider for your primary website, such as I do with Host Gator why not boast your ranking of both sites by using a sub-domain name yourself. For me my primary website is http://www.prosperyourmind.com and my blog site (sub-domain) is http://blog.prosperyourmind.com. So if you go to Alexa you will find my new blog site already has the ranking of my website. It beats starting from scratch and also makes a very nice bond in the rankings for me for both.
Let me explain that Alexa shows your ranking against all blog sites and does not have anything to do with your keywords, but it is a good indicator off the progress you are making with the popularity of your site.