DoTs and Haste Thresholds

[Revulva]

This post applies to Shadow Priests and Affliction Warlocks

TLDR:
1. The haste thresholds at which DoTs gain an extra tick do not matter for gearing purposes.
2. The value of haste at the "soft cap" of 50% does not diminish that much.

Example: Corruption - ticks 6 times, once every 3 seconds, with an 18 second duration.
- If you have 8.333% haste, it will tick 7 times and last for 19.385 seconds.
- If you have 8.332% haste, it will tick 6 times and last for 16.616 seconds.
Take a 5 minute boss fight as an example with 99% corruption up-time:
- With the 8.332% haste: You will need to cast corruption 18.05 times (lets say 18 times for 99% up time)
- With the 8.333% haste. You will need to cast corruption 15.48 times (lets say 16 times for 99% up time).

That is 2 extra corruption casts (2 GCD's or 1.385 seconds) over the course of the fight. 2.770 seconds. What could you do in that time? Cast... 1.2 shadowbolts, so basically one shadowbolt. Is it really valid to say that these haste thresholds are some sort of desirable gearing point? Being just under or over a threshold will not significantly change your DPS or total damage.

And, since the other DoTs a warlock uses have different haste thresholds (this holds true for spriests as well), you can only gear to hit one of these thresholds at a time anyway.

Another point regarding haste and classes that do significant damage with DoTs:
How much does it matter if your haste brings the cast time of your DoTs below one second?

Assuming a 5 minute fight with 99% up time:
At 00% haste: 1.50 sec cast, 15.000 sec duration, use UA 20 times to get 100 ticks.
At 10% haste: 1.36 sec cast, 16.364 sec duration, use UA 19 times to get 114 ticks.
At 30% haste: 1.15 sec cast, 16.154 sec duration, use UA 19 times to get 133 ticks.
At 50% haste: 1.00 sec cast, 16.000 sec duration, use UA 19 times to get 152 ticks.
At 70% haste: 0.88 sec cast, 15.882 sec duration, use UA 19 times to get 171 ticks.
At 90% haste: 0.79 sec cast, 15.789 sec duration, use UA 19 times to get 190 ticks.

If you cast UA 19 times in a fight with 70% haste, you do 19 more ticks of UA and lost 2.28 seconds of useful cast time over the course of the fight. So, at the expense of 1 shadowbolt (almost 2) you get 19 more ticks of UA. that's a pretty good trade-off.

A similar calculation would apply to Bane of Agony. You would lose about 1 shadowbolt there. Same with Haunt, you'd probably lose 2 shadowbolts there at 70% haste.

We'd have to run simulations to see if this loss in damage would make another stat more desirable. But, honestly, it's not possible to even reach 50% haste with the gear currently in the game. This was more of an interesting look at whether or not a haste soft cap at 50% really matters. For a shadow priest, I would say you lose almost nothing by gearing for haste past 50%.

[Revulva]

I'm adding information that I posted on EJ Affliction Warlock thread to help clarify this point:
for reference: http://elitistjerks.com/f80/t112939-affliction_cataclysm_dots_you/#post1834888

To clarify some terminology for non-locks:
ISF (improved soul fire) -15% haste
Dark Intent - 3% haste
UA - unstable affliction

If you have 580 haste on gear, your haste is:
ISF + Dark Intent + 5% buff + gear (580/128.05701) = 30.006% haste

If you have 581 haste, your haste is:
ISF + Dark Intent + 5% buff + gear (581/128.05701) = 30.015% haste

The interval of UA is the base, 3 seconds, divided by haste:
580 Haste Rating: 3/1.3006 = 2.30759 seconds
581 Haste Rating: 3/1.3015 = 2.30742 seconds

In a 300 second fight you will get:
580 Haste Rating: 300/2.30759 = 130.006 UA ticks, or, 130
581 Haste Rating: 300/2.30742 = 130.015 UA ticks, or, 130

You get an extra tick on UA at 581 haste rating, but the damage you gain from UA doesn't jump.

The only real "jump" is that the duration of UA at:
580 haste = 13.85 seconds = cast UA 22 times
581 haste = 16.15 seconds = cast UA 19 times

Cast time is 1.15 seconds, so, you gain a total of 3.45 seconds over the course of a 300 second fight. You can't even cast two shadow bolts in that time.

I think this is a very interesting mechanic, but, in the end, saying these "thresholds" are somehow important to our DPS as affliction warlocks or shadow priests is very misleading. We're already going to be tweaking our gear to have as much haste as possible. Would you really reforge away 50 crit or hit to squeeze in an extra shadow bolt? Would you change a 20int/20haste gem to 40 haste? Would that even be a DPS gain? The numbers we are talking about here fall within the margin of error in SimC, so it is hard to test.

Jmickey on elitist jerk's forum estimated about a 50 DPS "extra" gain for going from 580 to 581 haste. I would concur that this is approximately the value of the gain. Also keep in mind that this is the maximum value of the gain - each point of haste above 581 diminishes this "extra" DPS gain for hitting a threshold.