It is extremely hard as an OCE player to get arena queues in outside of the Tuesday night surge to get the 10 games in.
In retail, you can get queues any time of the day due to OCE being able to queue against US players. This reduces queue times and increases queue frequency.
If you are bringing in personal rating to do away with teams in WOTLK, please consider extending the people OCE players can play against.
Before anyone uses the “but the ping sucks” card, i have personally played at 2.3k+ mmr on retail as a healer which consistently puts you against US players and it was fine! 160+ms each game.
There are multiple Rank 1 players on Frostmourne & Barthilas (OCE retail) queueing against US players at 3k CR so the ping is not an issue.
I would rather be able to queue on 150ms than not queue at all outside of a Tuesday evening.