I had a very interesting experience with one of my sites happening for the last 4 months.
The site is for a professional service in a highly competitive market (NYC). There was an algo penalty several years ago that was recovered through new content and lots of quality links (mostly, media).
We were #3-15 for the main money keywords before we changed the site into Genesis. We tested the site on a shadow server where we put the no-index attribute in robots.txt. However, when the site was migrated back to a live hosting, we accidentally forgot to remove it, so the site got de-indexed by mistake.
The error was detected nd corrected about 5 days later, however the site did not appear in search for the next few weeks. After that, the site jumped bounced back. BUT, it had #1-5 positions instead on all money keywords. This lasted for 5-7 days, when the site bounced back to #3-15 positions again.
We've been putting a lot of investment and effort since that but the site never got back to #1-5.
Any idea on why this can happen? We have better links than competitors. The professional is a nationally recognized media person. There might be some older toxic links that give a little bit of penalty?
Thanks in advance!