I have a website, let's say www.example.com, that I added to Google Webmaster Tools without establishing any preferred domain. A couple of months ago, we decided to configure our site to establish example.com as the canonical URL, and redirect (301) all the www.example.com/bla/ URLS to example.com/bla/.
Since we did that, al the stats in Google Webmaster Tools (search traffic, indexed pages...) have dropped off. Our actual traffic hasn't been affected, only the stats that appear in Webmaster Tools. What should we do about this? Would it be as simple as just setting example.com as our preferred domain in GWT? Or should we create another property as example.com and merge them both somehow?