My guess is that at the end of the arena season the titles (gladiator, rival, challenger, duelist) are distributed according to the top teams, neglecting faction.
My suggestion is that the titles should be equally distributed to both of the factions (e.g. top Alliance teams get x titles and top Horde teams get x titles).
The reason for this is the idea of improving the Horde-Alliance strength balance which will consequently lead more people to transfer to the weaker faction (in Icecrown 90% of the top teams in the 2v2 ladder are Alliance players).