His passive says that "Evade a standard attack with high chance of succes". So his passive will likely to block one standard attack but there is still possibility it doesn't. If you are unlucky, he won't block that standard attack.

Yes, I get that. What I'm asking is if it's based on some stat or if it's a fixed chance.

It's a high chance, no stat you increase will make it occur, there is never a stat you can increase for things like that. It's just like Neji's Passive and Hinata's mystery.

It's not that good and fortunately he will get a Y version that will make it like madara 5k.

Anyway from what i have seen (with the exception of certain hit standards) he will always dodge the first auto. A friend of mine's Tendo (21k personal power) has always blocked my jonin minato's first standard (90k personal power).

Well, Tendo usually dodges Angel Konan's standard, but he didn't when I went against someone with 50k more power (also didn't dodge Kushina who attacked before Konan, maybe that's why?), so that made me think it depends on some stat.

Nah, generally if it fails on the first attempt, there is no more attempts.

You can see the same thing with Jonin Minato if you can hit him the first time in a round he won't dodge anything for the rest of the round.