Here's a quick explanation, then. Looking at a parse from Jaraxxus as blood, no GoD (World of Logs - Real Time Raid Analysis). It's a good example because there's nothing really out of the ordinary with the numbers-- abilities are in their correct proportions for doing a standard blood rotation, and HS average damage is dragged down only slightly by occasionally cleaving adds for reduced damage (the main and secondary hits are parsed as separate HS hits).

Avg PS damage: 4196.25
Avg IT damage: 2200.92
Avg HS damage: 6841.20
Total: 13238.37

Avg DS damage: 8803.26

Using GoD to refresh each rotation gives up a PS, IT, and HS in exchange for one DS. If I had used GoD on that fight, it would have meant a loss of 4435.37 per average 20 second rotation, or ~222 dps. Note that this loss is from simply using GoD. Factoring in the lost damage from not using GoDD adds another ~96 dps to the loss column.

GoD was largely dismissed for blood dps until it started rolling disease AP levels, the gain from which clearly outweighed the negatives. Now that it doesn't roll AP levels anymore, it's simply not worth it for single target situations.

It makes sense from a logical perspective, too. In Blood, HS is your primary attack. DS may hit harder most of the time, but it's a weaker attack per rune than HS. Giving up a HS and two other attacks just to gain a "free" weaker attack is not good sense. On the other hand, as you'd read in the unholy thread, GoD does become worthwhile at higher gear levels because the gain of the extra SS (your primary attack as unholy) is worth the tradeoff.

It's a loss of IT/PS for a gain of HS/pestilence. The amount of DS are the same in both.

You gain Heart Strikes using GoD not lose them. This is because you use Death Runes to refresh diseases in the normal rotation.

About the weapons. I get the Strength as being better without even considering it's slower speed.

How is the number of DS same in both?
Initially,
PS>IT>DS>HS>HS||HS>HS>HS>HS>PS>IT (No GoD)
PS>IT>DS>HS>HS||DS>HS>HS>HS>pest (With GoD)
Thats one PS,IT,HS vs DS, pest
Afterwards
PS>IT>DS>HS>HS||HS>HS>HS>HS>PS>IT (No GoD)
DS>HS>HS>HS>HS||DS>HS>HS>HS>pest (With GoD)
Thats 2 IT, 2 PS vs 1 DS, 1 pest, 1 HS
So GoD wins in the long run.
However, for short duration fights like Lady Deathwhisper p1, Gunship below zero mages, GoDD wins out.
In long duration fights such as DBS, GoD wins.
I guess it depends on the fight. GoD wins in aoe situations due to pest.

The "old" rotation was
IT>PS>HS>HS>DS
DS>HS>HS>HS>HS

You're apparently using IT>PS every stanza instead of every other stanza, which is flawed to begin with. If you sub in a DS for one of those IT>PSs, you get IT+PS vs. HS+Pest, exactly as he said.

GoD is the way to go currently with no foreseeable change in the future. Don't do blood dps without it.

I'm really confused on this. The fact that HS will be hitting harder than ever in T10 supports GoDD vs. GoD - if you lose a Heart Strike with GoD, which I was under the impression that you do.

You lose a HS to cast Pest, yes, but you gain 2 HS's by using death runes on them instead of reapplying diseases.

I'm having a hard time balancing GoD vs GoDD in 4pc-T9 atm, and anticipating what will happen once enough badges are out there for a split 2pc-T9 and 2pc-T10. Seems diseases will contribute less dps from breaking the 4pc-T9 set bonus, and without the rolling AP from the GoD glyph now.

As neomasterc said, it seems to me it'd at least be logical that we'd switch back to GoD once T9 gets replaced for T10 as I can't imagine GoDD's rotation outweighing the harder and more frequent strikes in a GoD rotation, and absence of critting diseases by then.

Thoughts?

Consistent with what I was thinking, thanks.

On fights like Marrowgar, I still find it useful to pop a quick pestilence before having to run out before Bone Storm, as well as when my add target is about to die on Lady and there are more to take out, so I guess it's situational for the time being. I take a hit in dps on Saurfang simply because I'm being overly cautious not to cleave the blood beasts, so it's hard to find a boss that's good for proper spec comparison parses as there's too many variables in the ICC fights so far.

It'll be nice to see some numbers once those T10 pieces are out in the wild.

I talked about GoD vs. GoDD only a page or two back. This is old stuff, but maybe it needs to be explained again.

GoD:

After your initial opening, your general rotation (provided you are never interrupted/forced by events and priority to change around the order of your attacks) is HSx2 {2B}, DS{FU} || DS{FU}, HSx5{2b3D}, Pest{1D}. (12 runes total, 4 blood runes, 4 death runes, 2 frost runes, 2 unholy runes)

For one attack cycle, regardless of the actual order of your attacks during combat (which may change for various reasons), you should have:

HSx7
DSx2
Pest (no direct damage)

GoDD:

Your general rotation is IT{D}, PS{D}, HSx2{2B}, DS{FU} || DS{FU}, HSx4{2B2D}. (12 runes total, 4 blood runes, 4 death runes, 2 frost runes, 2 unholy runes)

For every complete attack cycle, you should have:

ITx1
PSx1
HSx6
DSx2

Translation:

Not counting death coils, ghoul CDs, blood taps, etc, this means that by going from GoDD to GoD, you trade the damage of IT+PS for an additional HS (and associated Sudden Doom procs).

Math:

From my log of DBS this week, a largely static fight for melee DPS, my average Heart Strike damage was 7248 (removing blood beast cleave damage). My average PS and IT equal 5468 combined. This is a 33% damage gain over PS&IT. In addition, I would gain an estimated 660 damage per rotation via Sudden Doom procs. In other words, assuming 18 rotations (based on my number of heart strikes), in my gear I gain an average of 2440 damage per rotation with GoD.

Assuming 18 rotations, my additional Death Coil damage via GoDD and 3/3 Morbidity is 2530 per rotation. These numbers are a whopping 3.7% different, well within the conceivable margin of error for data from a 6 minute fight. This makes their damage benefit essentially equal in my mind, assuming perfect rotations.

Addendum:

In addition, due to the nature of each glyph's rotation, there are any number of additional factors that can come into play. For GoD, you must refresh at the last possible point to get the full benefit from the glyph. Refreshing one rune further ahead in every rotation will ultimately cost you 8.3% of the glyph's benefit, because you're losing that extra heart strike in one out of every twelve (eight?) rotations. In addition, you will not see the damage benefit for your opening rotation, starting you at a loss compared to GoDD.

For GoDD, you are less restricted in your rotation. It is much easier to squeeze in filler attacks without losing rune attacks, compared to GoD's risk of letting your diseases drop by overextending your rotation. The only thing you risk is using heart strike without bonus damage (which shouldn't happen) and maybe losing a tick or two of disease damage every few rotations.

Summary:

In the end it comes down to personal preference. The theoretical bonus from either glyph is almost the same (although I personally err on the side of GoDD being marginally better). The main difference is a small change in playstyle.

However, with enough ArP, GoD will probably outstrip GoDD. Since IT is unaffected by ArP, the average damage gain of HS will increase as you gain additional ArP, and obviously GoDD will not see a benefit from it. Since I'm running almost equal at about 40% ArP, I would guess that GoD MAY start to edge out GoDD by 50% and definitely will once you hit 60%.

UH should outperform blood on Marrowgar due to the whirlwind mechanic. On saurfang I think GoDD would perform best if you are being careful to avoid cleaving beasts, as this usually results in chopping your rotation, and filling pauses with as many DCs as possible. It may end up being entirely possible that while one glyph is theoretically superior, fight mechanics make the other the best choice.

I would say yes. Considering both the 2T10 bonus and the amount of ArP available on ICC gear, there probably will be a point where GoD becomes a clear winner.

I don't know if 2T10 will do it on its own or whether you will also need a minimum amount of ArP. Theoretically, 2T10 is probably enough, but considering all the things I talked about in the Addendum (and I can list more, like DRW use), I can't be sure.

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As someone else mentioned, another aspect is AoE. Any fight with unmitigated and constant AoE will see better use from a GoD, because you end up getting an additional 1.5 HSs every cycle (provided you are able to keep diseases rolling, which isn't always the case), and spreading your diseases is a built-in aspect of your rotation. In fact, if you were to pestilence with GoDD, this increases to 3 additional HSs.

However, it is also worth mentioning that, if you're of mind to switch glyphs merely for AoE fights, you might as well just have an Unholy offspec. It'll save you money on glyphs, and you will have superior AoE bar none. The stat weights between Unholy and Blood are very similar now, and the BiS gear will likely be almost the same.