#1 - Jan. 25, 2017, 4:28 a.m.
Explanation
Like the title suggests, I believe frost mages are losing some DPS by just doing their normal rotation. Brain Freeze procs are being lost because mages are following "Always Be Casting (ABC)" and queueing up a frostbolt directly after another frostbolt. Since Brain Freeze procs happen directly after a frostbolt cast is finished and you are queueing another frostbolt at that same moment you can't react to a BF proc until after the 2nd frostbolt is cast - at which point you might have procced another one, consquently losing the 1st.
A Brain Freeze Flurry does a lot of damage - somewhere around a million damage with crits on higher geared players. That's an awful lot of damage to miss out on by playing the way the spec was intended. It also seems like it will get worse on average when you get your T19 2pc bonus since you're more likely to proc a BF and lose one.
I took a look at the top 10 frost mage parses on heroic Krosus to see how it was affecting some of the best frost mages in the world. Keep in mind that in order to lose a BF proc you have to have one and the follow-up frostbolt has to proc one as well. There is some RNG to the number of procs you lose, but losing procs because of it happens every fight. Here's the results:
Heroic Krosus
Top 10 Frost Mages
# Procs Cast Wasted 2pc?
1 37 25 12 Y
2 37 29 8 N
3 32 23 9 N
4 33 27 6 N
5 32 24 8 N
6 25 21 4 N
7 30 26 4 Y
8 22 20 2 Y
9 37 26 11 Y
10 31 30 1 N
Average Procs: 31.6
Average Casts: 25.1
Average Wasted: 6.5
Average % Wasted: 20.57%
Sorry for the mis-alignment.
You'll see that some of the top mages in the world on a mostly single target fight are losing on average TWENTY PERCENT of their BF procs! I realize this is a small sample size, but if you keep looking through the logs you'll see the trend continues. I picked out random ones between #10-700 and the results reflected very close to above. Also, I have no idea how #10 was able to only lose 1 proc - he must have been extremely lucky IMO.
Some quick easy number napkin math. If each Brain Freeze Flurry does 800k and you lose 20% of them over a 4 minute fight with 30 of them proccing that's a loss of 6 BF Flurries which equals 4.8M damage and 20k DPS over the course of the fight.
Suggestions
My only suggestion is to make Brain Freeze able to stack to 2. This gives players at least a GCD to react to a BF proc and use it without losing it. We've had it before and it was great - please bring it back. This will both help frost mage numbers AND how the spec feels to play.