On twitter, a mage friend was musing how she'll often Ice Block if she knows a particular person is right behind her on the aggro table, especially if she just pulled aggro. She claims that she doesn't have it in her to play a warlock. I think this illustrates that she does, in fact, have it in her.
She just needs to go back to that special place, the groove she was in when she was "handing off aggro".
It's The Zone.
Just what is The Zone? Jong expresses it pretty well HERE and later HERE. Apparently a Belf Ret Pally's happy place involves flipping out. In that regard, we have much in common. That happy place is The Zone.
In our case, for a moment, we let go of everything that keeps our seething hatred of everything in check. We let that hatred flow out through our fingers as pure rivulets of pain and suffering and broken dreams. For a brief moment, we are not the base flesh that we regard in the mirror, but rather we are beings of pure shadow or fire or agony. We become these things, and we visit them upon our enemies. That is The Zone.
Consider the ending of Return of the Jedi. Palpatine was clearly a Warlock. When he starts to fry Luke's innards, his teeth are clenched in a grimace of pure hatred, and that lightning might as well have been coming out of his eyes.
He was in the Zone. That is the Warlock's special place. When you're wondering where your DPS went, invite Palpatine to help out, and it will all come back to you.
I am led to understand that the basic ennui of being a Shadow priest fuels DPS in a similar way. They have The Zone, too.
Find the Zone. Live in the Zone. BE the Zone.