The removal of the "deadzone" hunters used to have between their melee and ranged abilities helped me a lot in this regard, but apparently it hasn't helped enough. The addition of a Mortal-Strike-like healing debuff to Aimed shot, as well as a dispelling effect from Arcane Shot also turned out to be pretty useful for me personally in my PvP endeavors, and the new PTR buff to extra-target abilities such as Multi-Shot promises to let hunters use this ability much more often, without fear of breaking crowd control. The thing is, though, that the Aimed Shot and Arcane Shot changes didn't seem to do enough for us in the Arenas at high ratings either, so it's hard to imagine that Multi Shot will make a big difference for our numbers either.
So what's really going on? More and more it looks like Line of Sight problems really are the killer issue here. Blizzard can buff other hunter abilities a lot and they'll still be useless if good opponents can use obstacles to prevent hunters from being able to use them. If there aren't any practical barriers for people to hide behind, then hunters seem overpowered, constantly able to hit people from a safe range. Yet when these barriers are too easy to use, hunters seem underpowered, since anyone who wants to hide can just stay on the opposite side of a pillar. Coming up with practical solutions can be very hard.
The most obvious solution would be to change some of the Arena environments to reduce the size of the obstacles in question, such as the Nagrand Arena pillars, so that they are not so easy to hide behind. Blizzard has shown extreme reluctance to change PvP maps in the past, as in Alterac Valley, so I seriously doubt they'll consider this. Something inside me tells me that it won't really help that much anyway.
A different solution would be to buff Serpent Sting as a damage over time spell, and possibly open up other options for hunters to do damage over time abilities just the way that warlocks do, thus becoming less reliant on burst damage that the enemy must be in the open in order to use. Nobody wants hunters to become warlock clones though, so perhaps this isn't the best option either.
Another possibility would be to give hunters some rudimentary control over the movement of other players, either through a knockback shot (or pet ability) that could disrupt their dance around the Arena pillars, or some sort of magnetic trap that could pull them away from a hiding place. This sort of change would be unprecedented, however. Aside from abilities that slow enemies down, or stop them altogether, there aren't any which allow players to forcibly move them where they don't want to go. Blizzard likely won't want to give players such abilities where they've been avoiding them all this time -- still, it is technically possible.
A more likely choice would be to buff one or more of the traps so that it can reliably root players in one spot -- although we have a trap that slows an enemy down, as well as a talent which gives us a rooting effect now and then, being able to rely on a root would mean that chasing them around could actually get them quite stuck -- and from there we would have a chance to boom at them for a few seconds. Druids would probably be able to get out of it by shapeshifting, of course, but that's not just an issue for hunters.
Another possibility would be to make hunter pets a much more serious threat in PvP, especially for beast-mastery hunters. Perhaps some pet ability could be improved to the point that enemies would have to choose very carefully whether to run away from the pet and into the hunter's line of sight, or else stay where they are and risk the wrath of the animal in their face.
Although I'm all for buffing pets, the more I think about this issue, the more I like the idea of being able to chase my opponents into a kind of Entangling Roots trap. I'd be eager for hunter traps to play a larger role in the way we play the class in general, as well, and this would be a good step in the right direction.
What's your opinion on why hunters aren't doing so well in the Arenas, even in spite of recent buffs to the class which were designed specifically for PvP? What more do you think needs to be done?