I thought about myself when you made the comment about nervousness, how important mindset is, and most importantly, ass cheese.
I never miss ledge dashes, like hardly ever. I do however, miss wavelands on lower platforms when I'm nervous. and that **** makes me lose a stock half the time haha. Being chaingrabbed never bothers me, I consider it a part of the game and enjoy the challenge of getting even as soon as I regain control, even if it is with my next stock. I also love chaingrabbing people too (except against my homies in friendlies). I bet my most commonly made mistake is ignoring the importance of stage control when I get sidetracked. I start having fun, even if I am nervous, and go for something badass when I should have played it safer or tried to at least control the center of the stage... just leads to more disadvantageous situations.