So what would be better numbers for tank stats

I have already pointed out in the past text that the numbers they give for Defense, Shield and Absorption are horribly wrong, not only not even close to what they should be on a properly geared character, but in many cases even completely impossible numbers to ever reach.

More about that here:

http://noxxicsucks.blogspot.fi/2013/06/sith-assassin-darkness-pve-stats.html

here:

http://noxxicsucks.blogspot.fi/2013/06/review-of-noxxics-guide-for-juggernaut.html

and here:

http://noxxicsucks.blogspot.fi/2013/06/noxxics-guide-for-powertech-shield-tech.html

Now you don't see a lot of people giving the numbers in percentage anymore but rather as raw amounts of how much each stat you want with various stat budgets but even if Noxxic absolutely wanted to just give a percentage for each stat, they could have easily come up with much better by just taking a few minutes of their time to check few sources and to do a little bit simple math.

Here's how I would do it...

First we need to know what the base percentages for each class are, before the gains from the stats on gear are added to it, including  base defense, base shield and absorb from equipping a shield and shield gains from being in the tanking stance and all passive buffs from talents in their skill tree, but not counting skills that give temporary buff that is not up full time.

The base numbers with 0 stats on gear would be:

Assassin/Shadow: 16% Defense, 20% Shield chance, 24% Absorption

Juggernaut/Guardian: 8% Defense, 24% Shield chance, 20% Absorption

Powertech/Vanguard: 11% Defense*, 22% Shield chance, 24% Absorption

*includes 2% defense from set bonus for PT/Vang

Next we need to know the formulas how to calculate on how much percentage they gain from the stats on their gear.

Those are:

Defense Chance = 30 * ( 1 - ( 1 - ( 0.01 / 0.3 ) )^( ( DefenseRating / 55 ) / 1.2 ) )
Shield Chance = 50 * ( 1 - ( 1 - ( 0.01 / 0.5 ) )^( ( ShieldRating / 55 ) / 0.78 ) )
Absorb Percentage = 50 * ( 1 - ( 1 - ( 0.01 / 0.5 ) )^( ( AbsorptionRating / 55 ) / 0.65 ) )

Next we need to find out how much of each stat you should expect to have. There just so happens to be some good theorycrafting threads in the tanking section of SWTOR official forums that we can use as source for that information.

Now we need to just decide what defensive stat budget we should calculate our percentages for. The maximum you could have at 2.1 was something slightly over 2500, but with 2.2 coming up, let's just use 2600. I may have to revise that number later.

At 2600 stat budget

For Assassin/Shadow according to this source the optimal numbers would be 557 defense rating, 948 shield rating and 1095 absorption rating
This would give 23.46% Defense, 38.00% Shield, 47.07% absorption

For Juggernaut/Guardian according to this source the optimal numbers would be 1066 defense rating, 948 shield rating and 586 absorption rating 

This would give 20.65% Defense, 42% shield chance, 34.10% Absorption

For Powertech/Vanguard according to this (Note: I'm using different one for this one) source the optimal numbers would be 783 defense rating, 1089 shield rating and 728 absorption rating
This would give 20.93 Defense, 42.06% shield, 40.86% absorption

Just to be sure nobody misunderstands: These numbers are not any kind of caps or anything. They are simply estimations of where your stats should optimally be with one given stat budget. If your total stat budget is higher or lower the numbers need to be adjusted accordingly, just follow those linked threads.

Now let's compare...

Shadow/Assassin
What Noxxic said
Absorption (60%) = Shield (65%) > Defense (20%) >= Endurance > Willpower >= Accuracy (110%)
What they should have said
Absorption (47%) = Shield (38%) = Defense (23%) > Endurance >= Willpower

Note: There is a = and not a > symbol between defense and shield and absorption.
38% shield is of course without Dark Ward/Kinetic Ward. With them it (and set bonus) it would be 58%. A good guide should specify if the number they give is with or without.

Guardian/Juggernaut
What Noxxic said
Absorption (40%) = Shield (45%) > Defense (25%) >= Endurance > Strength >= Accuracy (110%)
What they should have said
Defense (21%) = Shield (42%) = Absorption (34%) > Endurance >= Strength

Note: Even though still not using "greater than" signs between mitigation stats, I am listing defense first and absorption last since defense is the stat you get the most and at much lower stat budgets they should even go all defense and no absorption at all.
Noxxic saying Absorption>Defense is about as wrong as you could possibly get it.

Vanguard/Powertech
What Noxxic said
Shield (50%) = Absorption (65%) > Defense (20%) >= Endurance > Aim >= Accuracy (110%)
What they should have said
Shield (42%) = Defense (21%) = Absorption (41%) > Endurance >= Aim

Note: The 21% defense is with set bonus. Without set bonus it would be 19%. This should be mentioned.

In any case, giving the numbers as percentage is really not the best way to give information. It tells you far less about how many mods with defense or absorption rating you would want than giving the numbers as raw amounts of how much each rating you want.
However even if Noxxic absolutely wants to give the numbers as a percentage, at the very least if they changed them to something little closer to what I presented here, it would be a huge improvement.

Of course there are hundreds of other things wrong in their guides which should be corrected too.

What about accuracy?
I would prefer not to have accuracy included at all.
Even if they absolutely wanted to mention accuracy, they should just say it is a stat to be avoided.
They definitely should not tell tanks to get 110% accuracy like they do now.
My previous post was about that:
http://noxxicsucks.blogspot.fi/2013/06/noxxic-and-accuracy-for-tanks.html