I think there is currently an issue with Blackrock realm, which stems from the following points:
1. Blackrock has a7 (relentless) gear available for free and effortlessly
2. Blackrock is on the same battlegroup as Icecrown and Lordaeron
3. Icecrown and Lordaeron players, aside from raids and months of successfully playing arena, only have access to a6 (furious) gear and 232 fos/pos/hor hc weapons.
I think the situation is unfair to Icecrown/Lordaeron players. People from blizzlike realms want to do PvP too, but we are forced to farm raids/10 games per week for MONTHS in order to compete with people from blackrock, who get all their gear in one minute after creating a character.
I suggest considering either of these solutions:
1. Put Blackrock on its own battlegroup, apart from Icecrown/Lordaeron
2. Blackrock players should start from lower gear levels (232-245) and climb towards a7/251+ lvl weapons like everyone else in the battlegroup.
I understand that it's a PvP only realm, but if you make a6/232 gear free, it would be enough of a bonus for a pvp realm.
even by removing blackrock from cross-realm you would still face a lot of Icecrown team with BiS players.
They have setted that enemy team from your same realm have priority.
So when you face "Blackrock teams", even when at low mmr, it is because there are no Teams from your realm in that moment.
So the alternative would be that your MMR become larger and you would face an "Icecrown/Lordaeron team" with BiS players. [BiS = full wrath/ 284 pve]
Btw I can agreed that for low gear players from Icecrown/Lordaeron is a bit frustrating facing "BiS relentless" players from Blackrock even when around 1500 mmr.
In my opinion to solve this problem they can just set that "Blackrock teams" can not face "Icecrown/Lordaeron teams" below 1600 MMR (or 1650) [to be applied ONLY for 2vs2]