As many players have noticed, changes to how creature health is determined in Patch 7.3.5 had a meaningful impact on some older raid content. This has been particularly noticeable in Warlords of Draenor and Mists of Pandaria raids. We’ve been discussing this topic constantly since the first threads popped up after the patch.
We want to be clear: our intention was never to greatly increase the difficulty of soloing old raid content for transmog or mount runs, but a side effect of the creature health tuning we did for leveling players. We’re currently working on a fix that will significantly reduce the health of Warlords and Mists raid bosses.
Thank you for all of your feedback and discussion on this issue. We’re sorry for the frustration, and we’re working to have you all back in there beating down those old raid bosses as soon as possible (hopefully before the weekend).