The yada yada and simcraft

I find it amusing that ppl go to ElitistJerks, watch the nice DPS bars with the different specs and glyphs and immediately say: This is the best spec, I use the best, so all other specs are for noobs. And so they behave like idiots.

That's all very fine if you have the perfect raid composition and exactly the gear stats as described by EJ and a perfect fight like Patchwerk and ....

HOWEVER... 99% of the time, you don't.

But still the funny ppl state the same things on wow-forums and such, e.g. that "Glyph of Life Tap" should not be used in Deep Destro, and should be replaced by "Glyph of Immolate". Why ? Because all high end players do it. And why do they ?
Oh... because simcraft runs from EJ tell them that. And so they do it.


Well, here is my EJ simcraft run, with my gear and my study which shows that Life Tap is not worse.

The only difference between the simcraft runs (that do the same nr of lifetaps since, on 5 mins target dummy fight, there's not enough mana) are the glyphs.

Data:
gear_stamina=1012
gear_intellect=748
gear_spirit=565
gear_spell_power=1879
gear_hit_rating=401
gear_crit_rating=408
gear_haste_rating=249
tier7_2pc=1
tier8_2pc=1
meta_gem=chaotic_skyflare
items=sundial_of_the_exiled/dying_curse
max_time=300
optimal_raid=0
talents=http://talent.mmo-champion.com/?warlock=000000000000000000000000000003220030003000000000000000005203205210331051335230351
actions=fire_stone/fel_armor/summon_pet,imp
actions+=/curse_of_elements/immolate/conflagrate/chaos_bolt/incinerate/life_tap
glyphs=conflagrate/incinerate/"immolate or life_tap"
infinite_mana="0 or 1"

Results with infinite_mana=1=> 0 life taps:
DPS(glyph_LT)=4120
DPS(glyph_IMMO)=4191
Results with infinite_mana=0=> 10 life taps:
DPS(glyph_LT)=4046
DPS(glyph_IMMO)=4023

Notice that DPS with glyph_IMMO is higher, but it decreases by 17dps for every life tap you do. DPS with glyph_LT is lower, but it decreases by only 7dps for every life tap you do. So we want to find the magic number of life taps for which glyph_LT is worth.
4120-7.4*x = 4191-16.8*x <=> x=7.55

CONCLUSION:
If in a typical (is there such a thing) fight I do 8 life taps or more, I should go for glyph_LT. Otherwise I go for glyph_Immo. And the difference... is not huge. Unless you do NO life tapping. So you ask:

Why should I life tap ?
1 - Taking in account most Ulduar fights require movement (Razorscale, XT, Council, Kologarn, etc, etc), You have to, anyway. How much ? Depends. A LOT. On gear, on RNG, on raid composition, on the skill of other players, their lag, your lag, etc.
2 - You need mana. Purists will say "but I dont need, I got the perfect raid". Congratulations. Most ppl don't.