Unholy DK issues in arena. 4800 resilience, etc

I am getting destoyed within 5 seconds, while I’m in blood presence with 4800 resilience. 45.43% damage reduction, yet I’m getting killed so fast. Anyways, I am lost for words and I am getting very confused over this.

Anyone care to exlain?

Thank you.

Destroyed by what? A single healer damaging you? A 3dps team in 3v3? An entire group of dps in a BG?