Hey there,
Our guild was having trouble with the second phase of Lei Shen, so we scoured a few good kills and found one with great positioning that has everyone spread out enough that still keeps everyone in range of the DK grasp. Thought I'd post my magnificent MS Paint skills of the positions up here so y'all can benefit too.
The general idea is that tank one (pref monk due to speed boost from their taunt) stands by the conduit, and pulls Lei Shen, ranged should be in purple locations by the time Lei Shen gets there, then tank two taunts him to the edge of the ring. Everyone is spread out enough that ranged shouldn't have to move much if at all to soak bouncing balls. Melee can scatter to soak them. Balls spawn and DK casts Grasp on lei shen's location. Stun lock them (Monk Leg sweep is best) and AOE hard.
The hardest part in practice with this is coming out of transition and getting to your positions, especially if you have Helm of Command, because then the number of ranged will be light and a ball will spawn in the melee pile, which as you can imagine is an instant wipe. Just call it out if you can't make it so a melee can run out behind the group.
To see it in action, this is the guild we got our inspiration from...who sadly doesn't know how to spell the bosses name...GG (They know how to kill him though, which is all I really care about, lol)
http://youtu.be/BoMR0_xIozI?t=3m41s