I don't think Hunters suck at BG's.
And I don't think it is you who sucks.

It is the case of being relatively undergeared, in relation to the playing field.
As the gear comes, and your experience with your team...

The ability to kill quicker and not be killed as quickly, will come.

PvP gearing a single toon in BG's, was a distinct pain in the ass, prior to boxing.
Some toons would not die, if I cast at their back as they beat a friend down.
And then they'd turn around and get me too.

But with gearing, I was able to take out groups of 3 toons, fairly consistently with 1 toon.
Of course BG's seem to be... no gear on 95% of the players.
And a ton of gear on the other 5%.