Tonearm - 3:34 pm on Sep 5, 2012 (gmt 0)
Do you have a Webmaster Tools account?
I do have one. I just logged in and it tells me for the single-word keyword in question my average position is 9.5 and my impressions look to be pretty steady over the last 30 days.
I dug around in Piwik and now I have this info regarding Google referrers from the single-word keyword in question:
September (thus far): 15
I just checked my rank and it's roughly the same on the 5th page.
In that case your traffic from Google should have taken a huge drop sometime during the past month. Did you see such a drop? The traffic is the true indicator of how your site is doing.
It's actually been the opposite due to my de-optimization. That seems to have more than made up for the loss of this keyword.
What do you guys think? Should I look into backlinks to see if there's something smelly in the mix? If so, what is the best way to do that?