That's pretty much impossible, to me it sounds like you just joined random bgs got rekt and decided to not play it anymore. Sure, it'll happen, but for starters you need to get PvP gear instead of playing bgs/arenas in PvE (Spam RHC for fastest eot gain which equals furious set), ask some friends to do duels and/or play bgs with you. Over time you'll get used to what other classes have against you, and how to play again them. When I first started playing I liked to watch people duel - learning which spells other classes have/use, how people with my class play against others. Then I started dueling as well when I reached full PvP (furious set, wf offset) - losing a lot in beginning and later getting into play and winning a lot once I got used to class playstyle.
The main reason I'm playing WoW is PvP, and yea, we all sucked hard when we first time started playing it. I do PvE too, but just over short duration then make a quite long break because I get really bored of it, then do again for 2-3 months etc. Doubt that PvE alone in SAME expansion can sustain anyone much longer.
Now, I know I derailed from the stuff you asked, but hopefully what I said will be helpful! :)