Plenty of features were changed during Warlords of Draenor, but none were so egregious as Garrisons. Garrisons were imagined to be World of Warcraft’s player housing. Players could put their Garrison in any zone, and could freely move it later. Followers would be fully customizable, and could complete quests, dungeons, and even raids on behalf of the players. Buildings would be highly-modular, with versatile placement, decorations, and multiple powers to choose from.
Almost none of these features made it to Warlords of Draenor. Garrisons were stuck in the Frostfire Ridge for Horde players and Shadowmoon Valley for the Alliance. Buildings could not be customized, could be placed in only a couple spots in the Garrison, and had specific powers. Followers were not customizable, and the rock-paper-scissors-like Mission Table replaced their dispatch. Other early ideas, like battle pet breeding, never made it past the concept stage.