AoE attacks look random to me, but I guess it hit nearest targets, which only the server can calculate.
If you want to spread bleeds evenly, maybe you should herd mobs into a big ball, and run round and round, spamming every possible AoE attacks. It also helps to lessen the amount of attacks mobs causing on you. Mobs that get killed will free the slots for other mobs, which will soon get the bleed spread to it.
Cool thing is that you can target one, Overwhelm to for cash-out, then Whirling to spread the bleed on that mob again.
[I]"Deserves it! I daresay he does. Many that live deserve death. And some die that deserve life. Can you give it to them? Then be not too eager to deal out death in the name of judgment. For even the wise cannot see all ends"[/I] - [B]Gandalf[/B]