Back in October 2012 I decided to pull the plug on a website I'd built on widgets.org. There was plenty of really good content but a load of spammy backlinks that were just too much to control.
I purchased a new domain with the same 'brand' on a different TLD: widgets.info. I shut down the old website and carried out a site removal on Google as per their instructions using the 'URL removal tool'. All that remained on my server was a robots.txt file and an index page which mentioned the new website location. There was no linking and no redirecting.
After I had observed that the old site was no longer indexed I bought the new site to life. I transferred the content over and made sure all of the images, links and database was sorted out to correspond to the new widgets.info domain. Everything worked as I had hoped for the first few months. I continued to add a lot of good content and did what good webmasters do (no shady link building).
In March this year I noticed my homepage rank start to drop quite suddenly. There was a bit of fluctuation before that time but it would usually stay on page 2-3. Now it dropped its way down to page 6. I also noticed quite suddenly that some of my old pages from widgets.org seemed to reappear in the index. If you typed in the brand name without spaces the .org version actually appeared a few places above the .info version. They were not cached and had no description or anything due to the robots.txt entries blocking crawling.
I went into WMT at this time (March) and noticed that the removal request had expired. Since I didn't perform any sort of redirects in WMT or elsewhere (no 301s, 302s etc.) why should this have any influence on widgets.info? In md-late April decided to cut out the robots.txt block and let widgets.org just return 404s for everything hoping that things would just drop out of the index naturally.
Things didn't improve, though, and if anything got worse. On May 9th I noticed my homepage rank slip further, now at page 10. I also noticed WMT informing me of a large increase in 404 errors on widgets.org at this time.
I want to have an open mind about this and know there can be other factors at play here (this is on Google.co.uk, incidentally, and I know how volatile things are there at the moment). It just seems like a huge coincidence. So really my question is this: Does Google ever form its own associations (algorithmic or otherwise) between websites in a way that the performance of the new domain is affected by that of the old.
I hope that makes sense.
[edited by: tedster at 4:53 pm (utc) on May 11, 2013]
[edit reason] defeat our forum's autolinking feature [/edit]