I use to like loading up on Alacrity to reduce cool downs. Now that I'm at higher levels, I find I've got plenty a stuff to do in a rotation and cool downs aren't such a big deal. Is there any drawback to not using any Alacrity, and just loading up on Crit, Power & Mastery?

CAVEAT: the below refers almost exclusively to DPS disciplines, although much of it applies to healers as well. I don't tank, so I don't know the best set-ups there.

You want Accuracy to reach 110% on the character sheet's lower part. FP and Ops bosses impose a passive (and not shown because it's assumed) ten percentage point debuff on the group members' individual Accuracy scores, and having 110% means they'll debuff you to 100% = no misses. Healers who do nothing but heal (bad policy) don't need any +Accuracy because healing abilities don't target enemies and don't miss either.

Alacrity has some weird behaviour, but the "received wisdom" is to let it get as far as 110% or so as well, and then not add any more, because you'll get more benefit from putting those points into Crit or Mastery/Power.

And the rest should be Crit, Mastery, Power, but I'm not really up on the best mix. (That said, wearing enough Accuracy and Alacrity to get the 110%, and then putting all remaining Enhancements and Augments into Crit seems to work pretty well for me.)

I use to like loading up on Alacrity to reduce cool downs. Now that I'm at higher levels, I find I've got plenty a stuff to do in a rotation and cool downs aren't such a big deal. Is there any drawback to not using any Alacrity, and just loading up on Crit, Power & Mastery?

Here's a great read on Alacrity in SWTOR: https://www.rambol.net/home/2017/10/24/alacrity-and-the-global-cooldown

To start off, I suggest going for 702 Alacrity and stacking the rest in Crit, Power, Mastery.

May I ask what class and spec you are playing?

I play mostly dps, which is where my question is directed. I am starting a healer, so would like to know if anything is different there from dps. My tanks are all geared as tanks not skanks, so there's no way I could get any alacrity at all. I have to put mastery, crit & power to give them some punch.

The biggest benefit of alacrity is highlighted in its effect on the global cooldown. But, the rounding of the GCD occurs in tenths not hundredths like ability cooldowns/casts/channels. Therefore, for the majority of classes, you only need enough alacrity rating to reach either the 1.4s global cooldown threshold (702 for most classes without any alacrity passives or procs) or 1.3s (1857 for most classes).

It is a true statement that a shorter global cooldown means you can fit in more abilities per minute which can increase your DPS. However, the benefit is only going to be seen if there is a fair amount of uptime.

If your window to do damage on anything, be it a burst window on an operations boss, or a marked target in pvp, is fourteen seconds long, then you will be able to get ten abilities in that window with a 1.4s GCD but only 9 if your GCD is 1.5s. But you won't see any benefit for that 1.3s GCD threshold if your window is only 14 seconds long. It will need to be 15 seconds to start seeing a benefit of 1.3s GCD over 1.4s GCD.

So, at 15 seconds:

1. a 1.5s (default) GCD will mean you have ten GCDs in that time
   
2. a 1.4s GCD will mean you still have ten GCDs in that time
   
3. a 1.3s GCD will let you get 11 GCDs in during that window
   

If your window is even smaller, lets say its a stun window, six seconds with a GCD of 1.5 seconds will be 4 global cooldowns. Six seconds with a GCD of 1.4s will also only be 4 GCDs. You'd need to go up to 7 seconds to get an extra GCD from the 1.4s threshold over the default, and 8 seconds to see an extra GCD from the 1.3s threshold. Getting all 8 seconds out of a hard stun for uptime is pretty good, definitely someone on top of their game in terms of reaction time and being in position, but I think many pvp'ers would rather have the higher critical for burst damage in 5 globals than get an extra ability in the stun window.

1. a 1.5s (default) GCD will mean you have ten GCDs in that time
   
2. a 1.4s GCD will mean you still have ten GCDs in that time
   
3. a 1.3s GCD will let you get 11 GCDs in during that window
   

One thing that's overlooked here is that, when you put more or less "points" into Alacrity, you also normally put an inverse proportion of Power and/or Critical. That is to say, generally, with lower Alacrity, you put more points into say Power, Critical, and/or Mastery (unless you put extra into Endurance, shield, etc).

This means that, although with high Alacrity you may get 11 GCDs within that hypothetical 15 second window, the DPS you do during those 11 GCDs would most likely be less. At what point it balances out, I don't know, but I tend to think that the 702 level (for the 1.4s GCD) may in fact be the "sweet spot" between speed (alacrity) and damage (Crit, Power).

EDIT - note that I'm only speaking generally. When you get into high level 252/258 gear with augments, you can, of course, run into the point of diminishing returns on several stats.

Based on my own (mediocre) parses on Lethality Operative in full 258 gear, I'm finding the sweet spots are 110% accuracy, 1859 Alacrity (1.3 sec GCD), and as much leftover into Crit as one can manage (I'm at around 1700). I feel like based on my fiddling that more is gained from Alacrity and Crit once Power and Mastery reach a certain level (can't remember the number but there should be plenty of posts in this forum that get into this in depth).

Obv my findings are specific to a particular class / spec - though I'm pretty sure there are several other disciplines that benefit from the same ratios.

I know there are quite a few far more impressive parses than mine on Parsely, but this shows my best numbers and i've only reached them with high alacrity. Still, my stats are a work in progress, definitely not as dialed in as I'd like.

Also I don't PvP so meaningful fights are usually plenty long to benefit from high alacrity - i get where PvP'ers would be better off with other stats.

One thing that's overlooked here is that, when you put more or less "points" into Alacrity, you also normally put an inverse proportion of Power and/or Critical. That is to say, generally, with lower Alacrity, you put more points into say Power, Critical, and/or Mastery (unless you put extra into Endurance, shield, etc).

 

This means that, although with high Alacrity you may get 11 GCDs within that hypothetical 15 second window, the DPS you do during those 11 GCDs would most likely be less. At what point it balances out, I don't know, but I tend to think that the 702 level (for the 1.4s GCD) may in fact be the "sweet spot" between speed (alacrity) and damage (Crit, Power).

Well, you don't want to put too many points in Alacrity Rating or Accuracy Rating above what's needed to reach the specific breakpoint in question, though stock 258 gear does make it difficult. It is still possible to reduce that "overage" of Acc/Alac slighty and gain I think an augment slot's worth of critical (i haven't done the math), but it requires buying healer set pieces for chest and feet and ripping out the enhancements, since the item modifications are bound to anatomic gear slot, which in turn requires a lot more MasDC.

Based on my own (mediocre) parses on Lethality Operative in full 258 gear, I'm finding the sweet spots are 110% accuracy, 1859 Alacrity (1.3 sec GCD), and as much leftover into Crit as one can manage (I'm at around 1700).

I highlight cibacrhome's post for the OP because its important. Lethality is a tech based class, and classes whose attacks are predominantly Force/tech yellow damage will benefit from pushing critical rating a little bit higher than the 1800 figure. By "1800 figure" I am referring to the point above which any additional critical rating adds less to dps than mastery. In other words, if you are a weapon damage (white damage) based class, you will get a little more dps by using Versatile (mastery) augments instead of critical ones, as long as your critical rating is at least 1800. But tech classes can push crit higher (especially healers.) This is all documented in that link from the poster above me, and also in these places:

The 1800 figure, as you may already know, comes from Schwarzschilda's work.

https://www.scribd.com/document/370568213/crit-DR

 

In the reddit thread where that paper was discussed, the original author (I'll abbreviate as Schwarz for convenience) later admits the limits of their theorycrafting (mostly limited to heavily weapon/white damage based classes) and estimated that 2235 is the better cutoff for tech/force-based classes.

 

This is also cited in the work that Rambol and Hottie did, from this thread:

http://www.swtor.com/community/showthread.php?t=945766

 

As a general comment, it makes sense that the critical rating cutoff would be higher for classes that are heavily yellow F/T based since the base damage of the attack is so much higher than white damage.

2235 would certainly be easier to hit if you went for the lower alacrity breakpoint, but it might be doable in 258 gear with 240 augments too, I just haven't checked the math. That being said, I would theorize that dot classes will get a little more dps benefit out of alacrity than other classes, because alacrity does make their dots tick faster, and many times dots will continue to tick and do damage on bosses even if you, the player, don't have uptime on the boss because of mechanics or whatever. Ranged classes may be able to avoid some anti-melee mechanics of bosses and thus may maintain uptime in those scenarios, and again may benefit from alacrity. Arsenal mercs/gunnery commandos, for example, have a discipline passive for 3% alacrity which allows them to run a lot more crit and still get the 1.3s GCD threshold. But, as a class that is heavily white (weapon) damage, they probably want to toss in a few Versatile augments if their crit is up to 1800.

Well, you don't want to put too many points in Alacrity Rating or Accuracy Rating above what's needed to reach the specific breakpoint in question, though stock 258 gear does make it difficult. It is still possible to reduce that "overage" of Acc/Alac slighty and gain I think an augment slot's worth of critical (i haven't done the math), but it requires buying healer set pieces for chest and feet and ripping out the enhancements, since the item modifications are bound to anatomic gear slot, which in turn requires a lot more MasDC.

I personally think that the healer pieces route is a little too extreme. At most it will save you arround 11 to 15 points in total.

The math for it is to not have ACC at all in all the pieces enhancements (i think is feet and gloves). Then use 5x 240 (cannot be 236) ACC augments and yellow (proficient) stim. That gives the exact 735 ACC needed for a rounded 110% Accuracy.

But, like i said at first, using the regular gear ACC + yellow stim would only waste like 11 points in extra acc. (but save you 10 Masterwork crystal, and a lot in the extra cost of the 240 augments that can be replaced with cheaper 236 Critical ones).

About that extra augment for critical you are right but its done with alacrity. Requires default 258 (head+offhand+2ximplant+ear) + 6x240 alacrity augments (i think 1 or 2 of those can be 236, but could not test yet as i'm missing 258 offhand). Before full 258, even with 236 augments one can end up wasting a lot of points in alacrity to get the 1.3s GDC as you require 7 augs for it. I'm 257 and it really pains me that waste.

This is not my research, it is based on this:

https://docs.google.com/spreadsheets/d/1tTZEODvA4-N_wLXlizG654Ii1z9gI88HavBk1WbTsk0/edit#gid=1340830784

That is what is considered full BIS, too expensive for my taste.

The math for it is to not have ACC at all in all the pieces enhancements (i think is feet and gloves). Then use 5x 240 (cannot be 236) ACC augments and yellow (proficient) stim. That gives the exact 735 ACC needed for a rounded 110% Accuracy.

735 gives you slightly less than 110%, and it doesn't round, so it still leaves you with a slight chance to miss. You've highlighted how much more difficult it is to get to 735, but it's also just the inferior way to gear for accuracy full stop. 258 boots, gloves, and stim gets you 746, which is the least amount of wasted stats while still being over 110%.