Hi Lisa,
you can add Google Analytics to track the value of the subdomain as seperate from the main. You would need to create a new property in Google Analytics and then place the snippet into each page of your blog site, making sure to not include the one from URL.com.
https://developers.google.com/analytics/devguides/collection/gajs/gaTrackingSite?hl=en
Hope that helps!
Good Luck!
Dana