Yeah, so first we started with the blogging and questions platforms and when the tag pages were getting into implementation, the UX team had a recommendation that the sidebar should go to the left side when it comes to filtering to shift focus from a usability standpoint. The recommendation is that the sidebar should be changed to the left also for the blog and question roll pages (roll page=list view of blog posts/questions), but technically it's trickier to change the full layout of an already built product than one that is done from scratch. That's why there is currently an inconsistency from a sidebar perspective, and the focus is on features/functionality/navigation/header.
Would be nice to hear your thoughts about which "side" you think is better 
Sidebars long term won't necessarily only have filtering options, but could also be a home for different and of widgets to get more personalized
Thanks,
Gabi