Generally after I change a site structure or do a redesign, some URL's are broken and not working. In those situations, you need to do the following:
-301 the broken URLs to new URLs
-Take an accurate snapshot of where your link building efforts are pointing
-Make sure you don't mess up a page that has tons of highly authoritative links
After you do that and change your structure, it's a great idea to build links to your NEW structure to build back any lost authority and start ramping up those ranking efforts.
Does that make sense?
