bluntforce - 8:09 am on Apr 28, 2012 (gmt 0)
That was a bad day to redesign url structure, results would be tainted by algorithm updates. If it's possible, make sure you have redirects in place from your old urls to the equivalent new pages. With a bit of time, and proper redirects in place, you should regain your previous rankings.
I've strictly been doing cosmetic work based on proportions of females vs. males actually completing my signup process.
It's not sexist, just working with established concepts of what groups find certain designs more acceptable and looking for higher conversion rates.