Are you usually dying during a stomp period, or an aggro-switch, or just randomly in the fight? And are these stomps rofl-stomps, or just normal stomps that you're not getting healed through?
I'm not in sunwell, so obviously someone else with better knowledge of the fight will be able to provide you some insight, but what i've come to understand is:
If you're dying during a tank swap, your healers are probably to blame.
If you're dying during a non-stomp situation, your gearing is definitely off.
If you're dying to a roflstomp, that's just bound to happen sometimes.
If you're dying to a regular stomp, it's either your healers fault or your gearing.
I peeked at your armory, and it looks like you went heavy in +15sta gems, ignoring most socket bonuses. Against Brutallus, from what I understand, you want to be using 5/7's or 10's for more avoidance (even to the point where you want 2 copies of T6 gear, one for EH and one for avoidance).
If you're having trouble dipping below 21k buffed hp, consider getting a warlock in your group for the extra stamina buffer? I believe 21k is your target for Brut, then stacking as much avoidance as possible.