As you already mentioned, in the upcoming patch there is a change to Vial of Shadows that should reduce some of the burst damage you are experiencing in PvP.
Dying in openers certainly isn't fun, and can be incredibly frustrating if you're the one on the receiving end of such a coordinated attack, but don't give up! In addition to perhaps taking some time to focus on other activities such as Rated and unrated Battlegrounds where you have more people to watch your back, you might also consider browsing some PvP videos from other members of the community to not only help inspire you, but to also arm you with a further arsenal of tactics that you can use to your own advantage against opposing teams.
Also, from my own experience, when I was having a lot of trouble against a certain class or spec that I felt countered my usual tactics, I found it helpful to sometimes grab a friend that played that class and spent some time dueling them so that they could critique me on areas where I could improve my skills, including my timing on using certain abilities, and how I could counter some of their own tactics. That way when I stepped back into arenas, I was more confident in my own skills and felt better-prepared for how to expose the weaknesses of my enemies.
Keep at it, and remember there are players out there equally as scared to see you step out onto the Arena floor. :)
Filovirus, a member of the defending champion NAO team, was doing RLS 3s earlier this morning. His shaman has ~4950 resilience. They ran into an RMP. The result?
1.69 seconds for 151,009 damage onto a target taking ~48% less damage? That's absolutely insane. No amount of practicing is going to help that.
Oddly, this RMP fought Talbadar's team as well earlier in the night. While they didn't get a kill on Talbadar's team in the opener, you can see the absolutely absurd amounts of damage this team can put out:
I don't want to chase off the first Blizz employee to post in the PVP forums in a long time, and I realize you're probably actually well aware of the situation, but I think this needs emphasis. This is absolute insanity.
Here's something else:
Watch the video of Cdew getting 3.6 second killed by Venruki, Original, and Sodah. [ http://www.youtube.com/watch?v=AT4uYNM32Y0&feature=player_embedded or http://www.youtube.com/watch?v=_mtcS1xtqM0&feature=related ]
Vial of Shadows is far from the only thing that needed nerfed. I mean, you're nerfing the trinket proc. That's good and everything, but what about mages? What about triple DPS just eviscerating the colons of their enemies? I mean, I'd attribute this to WOG off-heals, but most games end with the triple DPS' rogue outhealing the ret, so if ret healing is a problem, rogue healing is more of a problem.
I don't want to be a spoil sport, but the Vial of Shadows nerf will honestly do so little in the long run that I'd be surprised if it even reduced rogue rep above 2400+ from 16% to 15%.
I'll quote Filo on this one:
"People weren't even dying this fast in 5s last season."