I've had enough times in RJP to tell you of how ridiculous some things are in there.
Ever had a time when a Lumber hits a slime and it cannonballs towards you with a 360 degree no scope attack? Yeah. That will happen.
Ever had a time when a mini cube decides to be a snowball and hit you while you concentrate on taking down a group of enemies? Yes. And on my last pip.
Ever had a time when a time when the game says, "Curse you. You're dead." and lags you until you come back with your corpse across the room piled by jellies? Yes.
Ever had a time when you realize stun is a buff and will ice you sideways? Yes.
Ever had a time when you're using a slow sword while stunned and you stand there for 4 seconds unable to switch weapons while getting wailed upon?
Very yes so.
^^^^^^
Perfectly good things to rant about. Yes. Very.
/end rant
I am deeply offended.
Anyway, it sounds like you mostly need to practice. Improvement can in short be divided into three aspects: what bad things happen, why bad things happen, and how to prevent bad things from happening. You have very much succeeded in the first part, but you try to put the blame elsewhere, even though you can work agianst these things. Try figuring out ways to handle these problems, try those methods out, and see if it works.