Patch 3.0 was released not too long ago and there have been great changes to how PvP works. Some changes were good and other changes can be questioned. Blizzard feels that PvP is relying more on burst damage nowadays. Instead of waiting for players to get more health and mitigation, they felt a resilience change was needed.

The way resilience will work in the future is that one point of resilience will lower damage by 2.2% instead of the previous 2%. Also the maximum damage reduction from critical strikes was increased to 33%, up from 30%. The chance to get a critical strike hasn't changed and the dot and mana drain reduction will remain the same.

This means you should take less damage from critical strikes while wearing resilience gear. This change will affect existing gear.