Eyonix confirms new changes in the next major content patch that will affect DOTs and Resilience.  This will drastically change the latest Arena unbalance.

Eyonix: “Some of you already found the info, but here’s an official post from us smile

In the next major content patch, the combat rating, resilience, will also reduce the damage dealt by damage over time (DoT) effects. As it currently stands, each new tier of equipment adds to the amount of damage DoT abilities have, yet that damage is not mitigated through combat ratings found on typical equipment. This change will help ensure that DoT effects do not scale too well compared to other damage mechanics.

The amount of damage reduced will be equal to the critical chance reduction effect that resilience grants”