If you are getting pwned by Ascendance, you need to learn what a CC is. Its that simple. You allow a major DPS cooldown to stomp you, thats you being dumb.
I think the RNG aspect of it needs to be fixed. Sometimes you can do insane damage, sometimes you cant, it just needs to be put in a nice medium.
Its not just Shamans though, burst in PVP has been a problem most of this expansion.