v.1.7.5.0 once peaked at ranked 14 with my shaman deck + control rules. I upgraded and it now sits around 20 and will rarely hit 19. I uninstalled and re-downloaded 1.7.5.0 and from rank 20, zero stars, after 25 games I'm now rank 18, three stars with the same deck. I don't know what changed from these patches, but 1.7.5.0 is playing ranked very well as opposed to the newest update.

I know you said no A.I. was changed, but using the same deck and rules, on v1.7.5.0 got up to rank 16 before I updated to v1.8.0.0, and now that it's been running on v1.8.0.0 its at rank 20 zero stars again. But the arena mode is very very good, despite missing a few obvious card choices, and went 4-3 which I thought was pretty good.