Not a lot of Warlock mains because they're boring classes, I'm pretty sure a lot of raiding teams have warlock trials or alts because people saw lock dps on the meters and think to themselves: "WOW THAT LOCK CRITS 1MIL, I WANNA DO THAT TOO!" and they go to level a lock while they wait for WoD.
2 in my 25 raiding team. Sometimes only 1, but a lot of peeps in my guild are levelling one.