I guess a few things I would suggest for the arena is:
1. Reduce the waiting time, everyone is there at the same time and like BGs, there is honestly no reason for people to be waiting that long.
2. Reduce the amount of players in a single match, normally for me the que times during the end of the week become worse than Ashran.
3. Remove the starting raid group, it's kinda weird we are all buffing up the people who are about to kill us, would also end the annoying mage portal tricking. Plus it's kinda weird this gets an automatic raid group and Ashran doesn't.
4. Since you removed the raid groups you can group Horde and Alliance groups together to help Que times, honestly there doesn't seem to be a reason we are only killing the same faction.
Hopefully with a larger amount of players queing from Horde and Alliance and the no raid groups, they can also change to make it so groups aren't all put in the same match, or at least likely to all be in the same match.