Alright this may or may not be useful to you depending on your team make up and whatnot but me and my partner found it VERY helpful (: as the healer I was fishing in Dalaran just passing the time in between ques and i fished up a Magic Eater (Magic Eater - Item - World of Warcraft) I later ate it and it turned me into a cockroach! about 10 seconds later i entered arena and i still had it so me and my partner waited until 15 seconds and ate our food. Stormstriking cockroach much?! The other team didnt even notice me until i started healing. (takes you out of form) anyway hope this helps some of you (:
Edit : The well fed buff from the food does NOT work unfortunately
Summary:
1. Fish up/buy some Magic Eaters
2. Eat them just before the arena starts and join the battle
3. ????
4. Profit (win due to confusion)