How it is balanced
Tanks defense
Brutes scrappers offense.
Tanker vs Brute
Brute has fury... this makes a big difference in dmg out put.
Thus a brute can kill an opponet faster then a tank, so in a very real way they have a defense through offense ... a dead mob cannot do dmg.
In a mob of 10 my brute will kill 3 mobs when tank kills 2.
I will kill 8 mobs due to fury by the time a tank can kill 5.
This means a tank is taking a reduced dmg from 3 mobs where I am taking 0 dmg thus 100% resist becuase mobs are dead.
Apply this to stalkers too.
Now to balance tanks need better defense.
So they get that.
I am just glad we get the same -debuff. I could very well see giving tanks a -2.5% and us a -5% or even -5% tank and -7.5% brute / scapper.
How hard is it to understand that a dead mob = 100% resist or defense for that mob. And that a scapper/brute will kill mobs faster thus improve defense.
So there you go justification.