This is how it works. just like Ayame said.
When ally start making premades and only queing what they have best win rate in. BG's will be horrible for Horde and Ally will outgear Horde.
And since it starts on S1. Farming the marks for the gear Alliance have the upperhand.
I have seen this on many servers, Horde starts crying on Discord or on Forums for Ally to que so they can get the mark they need for the specific gear they want to get.
When it comes to Horde Racial vs Ally Racials: (Dont underestimate Alliance)
UD: Good vs Fears HUMAN: Stealth detection
TAUREN: Decent clinch stun. NIGHT ELF: Free Drinks in arena.
ORC: Good against stuns GNOME: Break Mage Shatters or Roots
TROLL: Haste mainly PVE focused DWARF: Free Cloak of Bleed/Poisions
BE: 1s Silence. (+RET Paladins) DRAENAI: Crazy Heal +1%Party Hit