If you want to get a closer look into defense mechanics you can take a look at this thread (from page 2) too:
Beat the 85
you cannot be crushed if "enemy miss", parry, dodge and block rise over 100.
the base crit chance is 5.6, the base chance to get crushings is 15 (from lvl 73mob against lvl 70 player)
melee crit = damage * 2, spell crit = damage * 1.5, crushing = damage * 1.5
to deny crits you must reach 490 defense skill, thats +140 defense skill which is 336 defense rating or with anticipation talent you need +120 defense skill which is 288 defense rating.
crushing blows can not be lowered that way but they can get pushed out of the attack table. to do that "enemy miss", parry, dodge and block must be > 85. which is easily done by activating shield block.
at the moment lvl 70 tanks can get some very sick dodge values while still obtaining a high block and some base parry.
its possible to get 35% block, 30% dodge, 16% parry and 11% enemy miss which lead to a very sick avoidance of 92 leaving only 8% of unchanged hits that will be always crushing blows.