As I already mentioned some time ago in a different topic:
The problem with den RNG in D:OS1 was, the gap between fail and success was to large. If a stun did not apply it should at least have applied a weaker effect with a bigger chance, increasing the chance of any kind of success.

The Delta of Randomness - Can You Balance for RNG? - Extra Credits:
https://www.youtube.com/watch?v=0V5eq4IQ6Go

More Ways to Use Randomness - What is the Goal of RNG? - Extra Credits:
https://youtu.be/GiOA_CS25Kw