You will have better information than I do, if you are running good analytics. But I wonder how many people access the site via the front page rather than directly to the forums (once they have access to the forums). Personally I forget the front page even exists. Content on the front page, shows up in the forum, so I don’t need to access the front page.
Just something to keep in mind. It may not be front page visibility that drives “trolls” but simply visibility within the community on the forum.