Tonight my guild killed Madness of Deathwing for the first time and Ti'tahk, the Steps of Time dropped, since the mage in my guild has the legendary staff and I am the only other caster dps i expected it to be given to me.
we ran 2 disc priests with atonement in order to keep up with the fight in terms of dps.
though after much consideration by the officers of my guild the staff was given to a disc priest, the disc priest with the lowest healing/lowest damage aswell.
the priest in 9th
now i guess i can see it going to a disc priest if they were given it for the right reasons. but...
the staff was given to the disc priest for the sole purpose of upping his disc dps/healing through atonement for heroic encounters.