Current game class vs class statistics is incorrect
The popup that comes up with information on the current matchup you are playing is incorrect. Under the Class vs Class heading, it seems to be pulling your overall win %.
You can see an example here: http://postimg.org/image/5l3tbytxl/
I only have logged games as Warrior, Druid, and Shaman, and this is the first time I played rogue, yet it shows Rogue vs Paladin as 84%, which is my overall win rate. Note that being the first time playing the class and being in practice for this screenshot are irrelevant to the bug, it was just the quickest way to grab a capture of the problem.
Fixed in 1.5.23, thanks for reporting this. I totally missed this.