Mages when geared and spec correctly, can absolutely demolish. I run a mixture of Naxx gear, Bc socket gear, and wrath eng items and tinkers.
however I have a lot more fun on my 60 Ret pally Haskey, killing 69s or 3v1 lvl 65ish. I have even got reported on my 60 with people saying I must be hacking because I’m killing 69s