The DPS Spreadsheet - How To Properly Evaluate Gear For Your Warlock

In order to evaluate how much better any piece of gear is over your current item, there must be a way to quantify how much of a DPS increase the piece of gear would give you taking into account your current spec and play style.
Every piece of gear that a warlock would be interested in, has various values in the following attributes:
Stamina
Intellect
Spirit
Spell hit rating
Spell critical strike rating
Spell haste rating
Damage done by spell (or shadow or fire spells)
Mana per 5
In the old days, I would assign a point value to every point in the above attributes; for example every point in spell hit could be worth 2.5 points in my system. Every piece of gear could be evaluated this way, and I developed a very large Excel spreadsheet listing every rare and epic piece of gear there was and has excel do all the math for me.
Today, there is even a better way. Let me introduce you to the Warlock DPS spreadsheet, aka the Leulier spreadsheet. Leulier has done the very thing that I always wished I had the time to do. He has developed a spreadsheet that can evaluate how much DPS you do can theoretically do considering all the raid buff, boss debuffs, and gear you currently have. In addition to this, he also provides a spreadsheet that lists every piece of epic gear in the game to help you quickly evaluate how much of a DPS increase a certain piece of gear would be.
I will not say that his spreadsheet is 100% accurate because there are too many variables in any particular boss fight. However, I will vouch for its ability to definitively and objectively compare individual pieces of gear. Every raiding warlock should be using an objective, mathematical system such as this to determine what gear aim for.
Here are some tips for using the Leulier spreadsheet:
1. Please realize that the XLS file uses a lot of VBA macros, and you will likely see a warning message about macros when you open the file. If you are concerned about macro viruses, then you should disable macros and examine the VBA code for yourself so that you are satisfied that it is clean. I've repeatedly used these spreadsheets without any problems, but that doesn't mean the site can't be hacked in the future. After opening the file, you should take notice that there are many tabs in the file (technically speaking each tab is a separate spreadsheet inside the file or "workbook").
2. The first tab is the Notes tab, ignore this for now as it has not been updated in a long time. As of this writing, the spreadsheet is version 2.6, but the change log in the Notes tab only goes up to version 1.20.
3. The second tab is the DPS tab. This is where you will setup the talents of your spec and select which spells you use in your spell rotation. For now, skip this and we will come back to it later.
4. The third tab is the Gear_Buffs tab. This is where we will start. You need to select every piece of gear you currently have from the various drop down boxes. The selections are coded to understand if an item has sockets, so be sure to indicate when gems you have in each socket, along with what enchant you currently have. Also towards the bottom of this spreadsheet, there are checkboxes you can select for your consumable and raid buffs. Under self buffs, be sure to check the Fel Armor box and select the type of flask, oil, and food you use. Under raid buffs, you should be able to check all the boxes except Judgement of Wisdom. Under Party Buffs, you should really leave those unchecked as you should not rely on being in a group with a shadow priest and/or a shaman; also change Vampiric Tough DPS to 0 unless you are certain you usually have a shadow priest in your group. If you are a leather worker be sure to enter 1 for Drums of Battle.
5. Now go to the DPS tab and enter all of the particulars of your talent build into the boxes at the top of the spreadsheet. There is also a template loader for some common specs that will fill in the talents with pre-set values. Be sure to check every talent to ensure it is correct. Leave the "Debufs", "Improved SB" and "Other options" at their default values for now; you can modify them later once you get more familiar with the spreadsheet. Under "Main options" be sure to select your filler spell; the filler spell is the spell the spreadsheet will assume you are using at all times when your other spells are not available for use. This is most likely your Shadow Bolt. Select CoS or CoE as your "Casted Curse", and select the type of pet you will either use or sacrifice.
6. In the spells table on the DPS tab, there is a column titled "used/option" next to all the spells we tend to use. Put a "1" in any box next to the spell name that you use. If you use a damaging pet such as a Felguard, then also put a "1" next to the pet; however, if you sacrifice your pet or if you pet does not fight (like an Imp), make sure it is set to "0" here. Leave "Life tap" set to "oom_time"; this will measure your DPS such that you run out of mana after a theoretical 10 minute boss fight (the length of time is set by the "OOM time" box under the "Custom LT/DP freq" seciton).
Now, finally you have your spreadsheet all set up with your gear, your talents, and the spells you use. The final answer you have been trying to get to will be calculated automatically for you next to the cell that says DPS (cell H33 on the DPS tab). You should take some time to try out "what if" scenarios. If you add or remove Immolate from your spell rotation, would that increase or decrease your DPS? Try the same with spells like Corruption; then what if you put 1 point in Improved Corruption, would that increase your DPS? It's this type of easy evaluation that makes Leulier's spreadsheet so valuable.
Below the spell section on the DPS tab you will notice a section called "The Next Stat". Taking into account all of your gear, talents, and spell usage, the spreadsheet has assigned a DPS value to every +1 point in the various attributes that is given to the gear we want. These values are the "final answer" that we need to know in order to properly evaluate potential gear upgrades.
Speaking of gear upgrades, now let's look at the Items tab. The Items tab lists every piece off epic gear available by slot. You first should press the button labeled "Sort Items"; this will sort all of the items by the DPS given by that item (including spell hit). A very nice touch to the spreadsheet is that the DPS difference (from the item in the list compared to your current item you selected in the Gear_Buffs tab) is color coded red or green and lists the actual DPS increase or decrease for you.
In some future post, I plan to go into more detail on some advanced options and features of the Leulier spreadsheet. For now I encourage you to use this. Start to investigate the details, the mathematics, and experiment with the options. There are other ways of achieving the same results as this spreadsheet, but this version by far is the best all-in-one spreadsheet I have ever seen. Leulier has truly made the spreadsheet I wish I had taken the time to make.
So after reading this, you have homework! Download the spreadsheet and enter in your gear and your talents. What is your DPS? Are there any spells that you should be adding to your rotation? Would a different spec give you better DPS? Check out the meta gems Ember Skyfire Diamond and Chaotic Skyfire Diamond; which of these would be better for you?
Feel free to leave any comments or questions! You can also visit the Elitist Jerk's thread on this spreadsheet to see more discussions on this.