Simple and short answer to this and that would be traffic that uses the toolbar. Don't worry about the Alexa site, just worry about getting traffic and your alexa should hopefully improve.
Alexa is generally useless unless you're trying to sell advertising to a company that thinks it's relevant and shows the value of your website. It's easy to cheat and get a better rank.
Alexa is not in the game with the big boys anymore! It's probably standing on its last leg by the minute.
http://www.doshdosh.com/20-quick-ways-to-increase-your-alexa-rank/ 20 ways how to increase you Alexa...