In a PvP oriented blog post on the official site, Lore revealed that spectator mode is officially a a feature for Warlords of Draenor:
Our new Spectator Invite system will allow a match organizer to invite two teams to play against each other in a PvP spectacle called a War Game. Then, when the match begins, everyone in the match organizer’s party will be able to watch those two teams duke it out. We’ll also be opening this feature up to add-on developers so they can come up with tools for tournament organizers to customize how the match is presented on the screen.
Other updates for Warlords’ PvP include the death of the Trial of the Gladiator feature due to community concerns and the return of skirmishes.