I suggest this be moved to the elite section as the widespread knowledge of elite exploits always results in an early hotfix.
This exploit allows you to move freely in the arena zone before the match starts.
I am sure there are many tech savvy people that can find ways to do this without uninstalling but I actually stumbled upon this by coming on my ship offshore and deciding to come back to the game. Blizzard has a feature for world of warcraft that allows you to play the game before the install is complete. I have done this many times and believe optimal use of this exploit works around 16-35% of the games complete download. I would suggest throttling your connection in some way or using a mobile hotspot or wifi connection that may be limited to a low internet connection. If you have an extremely fast download speed you will not find use of this exploit for more than a few hours before you have downloaded all of blizzards boundary restrictions.
The number 4 below is very important. If you should join a game without seeing the class / race of your enemy you will not be able to target them.
The Dalaran Sewers arena match for some reason is the only one that allows you to still move past the starter zone past 35% install. I haven't yet found at what % download exactly this stops because I didn't roll Dalaran Sewers many times.
I would suggest moving just to the side of their gate so not be seen immediately when they are allowed out. I have found this is extremely fun as two dps because you can easily knock out 1 player quickly before prepared.
I have found a few bugs with this exploit for instance in dalaran sewers you can get stuck in the boxes that are on the upper platform. Someone should report these bugs and have them fixed haha!
To do this exploit follow the instructions below: ( read the tips listed above )
1. Wipe world of warcraft off the drive you intend to play from.
2. Download the installer from the blizzard website.
3. Start the download and log in the game about 10% of the downloads completion.
4. Move to a major city and make sure to see a character of each race and class.
5. Find a partner ( really fun with someone else doing this ) and que for arena.
6. Upon entering the battle notice that there are no boundaries binding you inside your starter zone.
7. You can now move freely even sometimes into their starter zone.