Nice and your right,with CC and esp mages AoE which every Arena team seems to pack atm,I struggle to get off one maybe 2 rotations.
But one thing that greatly increased my damage as a Frostie was:-
Horn of Winter (UP)
Chains of Ice/or Icy touch
Pestilence
Deathchill
Howling Blast
IF you can also get 5x D&D at the start it really helps melt them down,but atm I find it difficult.
I'd be interested in how after the patch things go for you in Arena and BG,especially with frost.;p