Hybrid is a bad word and those who use it should feel bad.
"Tank" isn't a role in pvp really, since it's not like you can taunt and threat on people. Warriors and DK shouldn't come under your random umbrella, since all they can really do is deal damage.
OT: Ret/Enh/Feral would be hybrids, Wars/DK's no. You know, since the only things you can really do in pvp are damage and heal. My taunts don't seem to work for some reason.