Hoople - 7:20 pm on Oct 10, 2013 (gmt 0)
Did your backlink profile change before/after? This might indicate somone else's cleanup efforts had a positive benifit for you.
What I did to achieve this - absolutely nothing.
Those still seeing a decrease *may* be due to a lower quantity of quality IBL's (not devalued by Google) and thus its effect on ranking.