tedster - 3:44 am on Apr 9, 2013 (gmt 0)
hard to find the exact reason
Even long-time SEOs are scratching their heads a lot lately. One key to getting somewhere in your analysis is ruling out one explanation after another... something I believe you just did.
Also, as crazy as some effects look, I try not to be very quick to say "Google's algo has an issue." I thinkk they are creating the SERPs that they intend to a lot more than some people are willing to credit. The big question is why they want the effects they are creating these days.