Patch 5.2.0b Edit
Patch 5.2.0b is the unofficial name for the patch build 16683 that came out a few days after the unofficially named "Patch 5.2.0a" build 16669. There is almost no info on this patch build and there has been no official acknowledgement of the release of this patch build. This client could correspond to the March 11, 2013 slate of hotfixes.
See also Edit