A new ladder system
Right now, our biggest issue is probably ladder reliability. We're working on a new ladder system entirely to replace the old one in the coming weeks, so be prepared for a ladder reset – all your ladder rankings will be wiped soon!
No visible changes are planned – we'll still be using Elo mainly, and Glicko-1, GXE, and COIL for certain specialized situations.
However, third-party servers will have their ladders stored locally, which means that unregistered servers will also be able to have ladders. And the official server's ladder will be rewritten to be faster.
—Zarel on Aug 8, 2015