btw all the arena servers are located in west coast
It doesnt work like that.
There are different blizzard servers located in different places, when you join arena if you face for example a 3x russian team in eu they re hosting the game in their east europe server if you re playing with people that doesnt have the same server as you, the other team will always host the game.
For example, if im playing from dun modr ( spanish realm, server located on france) with people from outland or ravencrest (server located on denmark or germany not sure) and we face a 3x russian team they host the game all the time, and my latency might increase to 150, if i play with another 2 spanish then its random, cos theres 3 people from the french server and 3 people from the east europe server, i had a conversation with novoz about this and he said it works like that aswell on US, so in that way if you face a 3x aussie players playing from an aussie realm and you have 1 guy on east coast realm 1 on central and 1 on west coast or anything that its not 3x the same realm they will host the game and you will end up having more than 200 ms, nothing you can do about that.
I would say you could ticket blizzard and ask them about do some middle host protocol, for example if theres east coast vs aussies then the west coast server should host the game but im not sure how receptive they will be about that, its not a easy task as a server administrator