I don't consider myself a "great" Warlock but I do consider myself a "good" Warlock ... every now and then I can have world-class performances, but it's hard for me to stay consistent over long periods of time. I can make use of a great deal of the for-the-elites tactics, but not all of them, and not consistently.
But then, I haven't had nearly the amount of free time I used to in order to just hit the target dummies for a long time each day, sim every possible itemization (gearing, reforging, etc) choice I had available and hit the dummies as each one, etc, etc ... I did a lot of that (well, mostly just the dummies, and my initial class research) when I realized I was terrible as a dps-er (for what I wanted to do -- but, hey, at least I took the time to research what I needed to do to get to where I wanted).
And also when I realized that with proper knowledge and while properly-utilizing addons and such, I could play at or even above the level of the people who helped me understand how bad I was and helped me get better, I really dug into the simming and such, hitting the dummies as each spec in each gear/forging combination to see how each sim compared to real data (relatively-speaking of coursre, considering the differences between a Patchwerk encounter and the target dummy).
Bleh, I gotta get back to work ... but, yeah, I hope with the intentional attempt to somewhat close the theoretical gap between the floor and the ceiling of dps performance for various specs, particularly the Warlock ones (how much or little they succeeded remains to be seen, when we get release builds, I guess), that the point on the spectrum I currently occupy is still in about the same relative spot, rather than the level of performance I can give isn't enough to cross a threshold between decent and elite that with the squeeze actually skews towards a lower ratio of players able to perform at the higher levels.