tedster - 9:49 pm on Oct 7, 2012 (gmt 0) [edited by: tedster at 11:45 pm (utc) on Oct 7, 2012]
False lead = "Maybe this link has the information I'm looking for." - "Whoops, no it isn't. Maybe I'll try another link here first instead of going back to Google right away."
Just one scenario I thought of that could match your shift in stats.
I'm very interested in the results of your shift to an inverted L navigation. I know it hasn't been in style recently, but sites where I use it still seem to thrive and sites with other trendier approaches often seem to struggle.
Not that such a change would DIRECTLY affect a Panda demotion, but it certainly might do so indirectly.
[edited by: tedster at 11:45 pm (utc) on Oct 7, 2012]