Hello,
dunno if it was stated before, but i just found out a nice bug.
I invited a friend by accident into a team. He was afk, so he didn't accept the invite.
I started the arena match, and after few rounds, voila, my friend un-afked, accepted the invite, and threw me out of arena match. The sound of the match was still in background, and i was out of arena match. Resulting in, you guessed, a nice loss of arena points.
Make a fix and disable team invite if someone is "busy" with some other things.
Thanks