Where are the number coming from for "stuns from behind"
 

It seems i'm getting sunned about 90% not even remotely close to what it's supposed to be so trying to figure out how this got implemented in such a manners.

if your feeling it bad now, the pre patch was absurd would get stun 110% of the time.

Probably counts as a standard "proc".

Good thing mobs have low proc rates.