Usually if a DK is resource starved for a long time and several times a fight, it usually means that they do not pay attention to their runes or use them effectively. I'll try to explain as best I can.
Every DK knows that the priority is to fit in as many Obliterates (with Killing Machine) as they possibly can, as it is our hardest hitting ability. That would not be a problem at all if we work on unlimited resources but we have a unique resource type - 6 runes and Runic Power.
F - Frost Rune
U - Unholy Rune
D - Death Rune
Now think of those abilities and what do they do in terms of resource:
Obliterate: Costs 1F 1U/1D, gives 31 RP, chance to proc Rime
Howling Blast: Costs 1F/1D, gives 21 RP
Frost Strike: Costs 32 RP, chance to proc Runic Empowerment
Okay, so how does a DK run out of resources?
Simply put, we use up all our Runes and Runic Power BUT Rime or Runic Empowerment did not proc.
This is the point in the fight where you have almost all runes up and high runic power.
Three runes left and about 60 RP
FfUuDd < lowercase is rune in the process of regen
Now here's the interesting part (and more relevant to the post).
Say you have 1 Unholy and 1 Death Rune up and very little RP. This is a common thing I see a lot of DKs do.
Killing Machine procs, hit Obliterate immediately.
- Rime procs - Howling blast > Frost Strike > Runic empowerment does not proc > Wait 5-6 secs for rune regen
- Rime does NOT proc but have 32 RP - Frost Strike > Runic empowerment does not proc > Wait 5-6 secs for rune regen
- Rime does NOT proc but not enough RP > Wait 5-6 secs for rune regen
So how does one avoid this?
Well, to a certain extent this is based on RNG. However, one can always expend their runes in a careful manner so as to not reach that point where bad RNG will place them into a spot where you have nothing to use for 5-6 seconds. Of course, this varies across different fights and different phases of fights. If I were in a burn phase and the boss dies in 10 seconds, damn the resource and spend everything!
Another tip: I see you have the Eye of Unmaking, try to wait till it's 10 stacks before popping CDs as to have maximum uptime of maximum strength. Also, watch out for Fallen Crusader (rune forge) and Runic Mastery (4pc) procs to help yourself make better spell selections. I only looked at your H Morchok parse. If you're not staying in for Black Blood phase, you should. It will help your uptime and dps by a lot. There are a lot of other things you can do, PM me if you want a lengthier how-to.
Aniana on Tichondrius (My DK)us.battle.net/wow/en/character/tichondrius/Aniana/advanced
Here's my parse one month ago when I was still in at least 2 pieces of T12 gear as you can see from the Smoldering Rune buff under Buffs Gained. I hope this helps a bit and I'm sorry for any misinformation (fully unintended)worldoflogs.com/reports/rt-nkyodc1p6704smd1/details/210/