Recently a website for which I'm doing SEO has been hit by a decrease in rankings for several key terms it was ranking very well for before this "penalty" hit. It only concerns the homepage and it only concerns certain key phrases, therefore I strongly suspect this was due to some "algorithmic anchor text based penalties" for several key phrases.
Reason why I also think this is that because in the few months before this penalty hit, a lot of link spam was added on various external websites. This link spam was added by competition! Someone has posted links with keyword rich anchor texts on a large (easily 100 or so) number of websites, often sitewide. Shortly after this was done the penalty hit and decreased rankings for the exact same phrases that were used as anchor texts for these spam links.
This is clearly a signal of negative SEO, I know people sometimes claim that negative SEO was applied by a competitor while this in reality was not the case, but in my case I'm really sure that it must have been someone doing this on purpose, I have never seen this many links appearing on such a large number of very low quality websites, almost all sitewide as well.
First I had submitted a reinclusion request to Google but I got the reply that no manual spam penalty was applied. This makes sense considering that it was more like "algorithmic anchor text based penalties" which would be automatic rather than manual.
The weird thing is that the spam links have already been removed again, they only remained online for a month (or two) or so and are now gone. However, the negative influence on the rankings remains, the rankings did not go up again yet.
I'm now wondering whether it would make sense to use the disavow tool for the external links that have caused all this even though they are not online anymore. The links can still be found in Google Webmaster Tools (as it of course usually still shows also links that are already gone). I could therefore use the disavow tool to try and see whether it would have a positive effect on the rankings.
Before I try though I would like some people's opinion on this. What do you think? Does it make sense to try this?