When I changed the URL structure of my site I didn’t migrate the links using 301 redirects because I didn’t have the time. As the weeks slipped by, my traffic dropped significantly. The Intelligence Events section in Google Analytics can give you an overview of major events happening on your site that you may not be aware of. The details link also provides great insight and really shows perspective. Here’s an example from my site:
Here’s a great video from Google that explains how you can customize the Intelligence Events. The customization can be very advanced or simple. Nice!