Its like you forget that frost recently got a massive buff recently. Deep freeze critting for 30k and using FFB instead of fireball for brain freeze procs...
I had a friend who usually does roughly 8.5k DPS on saurfang10 as arcane. He did the first wing as frost for the lols after the deep freeze change, and was only about 1k dps less than his usual all the way through, hitting about 7.6k on saurfang.
It really isnt that bad.