Right now DKs are punished for not using their ultimates as soon as they are up. ZoS has been reluctant to adjust Battleroar, and after seeing the issues with Balorg, this may be due to a coding issue.
Instead of asking for a buff, how about asking for a band-aid fix; DKs get cost reduction based on current ultimate.
+100 ultimate-3% cost reduction for all abilities
+150 ultimate-6% cost reduction for all abilities
+250 ultimate-8% cost reduction for all abilities
Numbers could be fine tuned, but the idea is to reward DKs for holding onto their ultimate, so as to diminish the current downsides of Battleroar