I got my surf pikachu with just slightly over 8,000 steps. since then I've only gotten a !!! patch one more time and that was over 10,000 (although it ran...)
So it was just my bad luck. But when I had the 9000-ish steps all I got were "!" and an occasional "!-!", and I reach 10000 and I get a "!-!-!!-!!! on like my 3rd try."
Did you capture yours in a !-!-!! or a !-!-!!-!!!? Becuase it could be possible taht the !-!-!! start appearing 8k+ and !-!-!!-!!! appear 10k+.
And like said before me, to completly show causation we need to remove any possible lurking variables. So we are going to need many different pokemon of diff wieghts/levels/etc. On the critcal hit discussion.
If only we had a research thread to assign people jobs. ;(