Robert_Charlton - 8:48 pm on Oct 2, 2013 (gmt 0)
...focus mainly on long tail keywords in a highly competitive consumer goods product.
This part of your strategy also needs examination, particularly in the context of a competitive market with zero backlinks.
Note that targeting longtail like this is essentially what the content farms that inspired the Mayday update were doing... and that Google has continued to go after sites that specifically target rare longtail phrases.
I suspect you'll have less and less success with this over time. Chances are your pages got a freshness boost for a while... and that they were longtail enough that they may have flown under the radar... but I too was surprised that the pages ranked at all.