"Green Vial (Adds!)
Every third vial will always be green.
Maloriak will coat everything in the room with Debilitating Slime. This increases everyone's damage taken (including Maloriak's), but more importantly it temporarily (~15 sec) counters the protection buff the adds mentioned above have. As a result: when adds spawn, it's best to have an off-tank pick them up until the green vial phase, then AoE them down."
Source
The difference of dps is too big to be just 500ish mastery vs 500ish haste(if same gear assuming he has reforged his stuff into haste, and u ur stuff into mastery), although I maybe wrong.
I am not "following retail guides blindly" mate the way I am not following what you say blindly, I am trying to figure out what's going on, like the rest of the people here. There is no need for a violent tone.