Personally, Iíd say no. I have clientís sites that do well with LSI type relevance terms that we havenít even optimized for. We have also had success implementing LSI strategies. I would have to say itís something else.
Agreed. It must be something else. Google has dozens of factors that go into play ... and they also do algo shifting. You may have done your changes during an update and what you thought was a decrease due to LSI issues, was just a decrease as the new system devalues your page.