Where do the visitors come from? How are you sending targeted traffic?
PS: Having a patent does not mean that the patent holder is using the patent. A patent can also be used to prevent competitors from using a technique or to protect a method that might be used. The patent does not state that it matters in search results. It simply is a method that could be used to extract information about traffic. The overwhelming majority of web sites do not expose their server logs, so the use of the server logs to enhance search results is useless.
There is no evidence that Yahoo is using server logs to influence search results.
"It's inexcusable for scientists to torture animals; let them make their experiments on journalists and politicians." -Henrik Ibsen