I ran into the same issue -- I just upgraded my Battlemap Hide Helm (a blue) to an epic PVP Helm - Titanforged Leather Helm of Dominance. It was definitely an upgrade. In fact, if you click on the arrow next to my helm and check the listing at wowhead.com, the PVP helm is ranked 5 slots above the blue one.
I dropped from 1988 to 1976 because of this.
Looking further at the items, I basically gave up +crit for +hit, which is definitely preferred for raiding as a boomkin. Additionally, the PVP helm has a red socket for the potential for a lot more raw damage.
Glad these PVP issues are being discussed here!
Shajshas, Alleria Realm (US)