For several years, I was ranking very well for a few keyword phrases which generated a small, but steady stream of referrals. Over the summer, my main site blew up. All of my clients had problems with their sites (major server issues...) and I had to fix their issues first. Mine was "more broken" than theirs because I could not retrieve the database.
In the fall, I rebuilt the website (new server - similar setup) and used archive.org to get my articles back. (No I didn't have a backup. I do now!) I came right back for my big phrases immediately thereafter, albeit a bit lower in the rankings. I used WMT to remove broken links, used htaccess and internal CMS features to redirect lost traffic, etc. I began writing articles again.
Sometime since then, I noticed I don't rank for anything anymore, just my business name. Not even close! Even with the site down, I still got distant rankings. The odd thing is that it took a few months and by then the problems were fixed.
Before - #1- 5
While broken = #20 - 35
After rebuild = #10 - 15
Now - #450 +