I don't have issues with him being able to avoid attacks, i will not question it. I have an issues with his character altogether.
1) He is "supposedly gamer" and one of the tops as well. Then his "agi-build" already goes against most of the "gamer basics". Even if he want to experiment things, he did it way too fast without thinking, there is no way that "supposedly gamer" will do that.
2) Seeing how efficient evasion is, i 100% sure that if he had all those skill-points in defense instead, he would be even more efficent, especially because even if something UBER-powerfull can scratch him, his regeneration spell will heal it faster than he receive damage.
So, for that point, his character sheet is already gimped, and it's only ok for him, because he had ungodly 150 points at lvl 1.
3) His face is so punchable and his cocky smile so disgusting. It's really rare case when i want to punch MC more than that fat king and his cohorts.
4) As a "supposedly gamer", he should know how parties created. It's ok that he is trying gimped build for entartainment, but he should be aware how everyone else will see it, and will just not take a risk to try it together with you. The way how he tell everyone that he is "evasion healer", when nobody even asking him is disgusting. I blame mangaka for this, but WN probably the same, so the original autor is to blame too.
Gamers have tons of ways to not disclose info about their builds, or atleast say something to divert attention.
I understand that if not all of this bullshit, it wouldn't be a story... but atleast don't make it like he had a plan, and it worked. No! He is stupid, he fucked up, and luckily his life still somehow doable. That's the manga about the idiot that "pointed finger at the sky", and luckily his choice didn't turned into immediate death.