diberry - 3:34 pm on Sep 20, 2013 (gmt 0)
shaunm, I have exactly the same issue. I have a site that's been #1 for "keyword phrase" for several years. Even with personalization, Webmaster Tools still reports it being 1.1. According to Adwords keyword tool, search volume is about 14800/month, and that is actually about the number of visitors I used to get for that exact keyphrase. I double checked where it says "keywords like..." but it only listed my keyphrase, so this is not lumping lots of keyphrases together.
But somehow over the past year, my traffic has dwindled to about 1/10th of that - around 1400 to 1600 per month. Why? There are no ads with this particular keyphrase - never have been, so it can't be people are picking those over my organic #1. And it's not personalization, or else WMT (and my analytics package which picks up precisely what number they clicked me on) would show something lower than 1.1. Are people just not clicking #1 anymore? I doubt that!
So I don't know. #1 used to be worth a LOT more than 1/10th of the exact search volume because the vast majority of people click #1. Now it doesn't. Something has changed, I just can't figure out what.
I'm glad you started this thread, though. I've been considering it, but thought I was the only one and maybe it was something peculiar about my niche.