[Coolboyrulez0]

It's this simple:

If you miss you acknowledge that you are unable to hit certain parts but you still hit the all the notes that you know you are able of hitting.
That is acceptance of one's inability to hit said notes. That is skill.

Now, mashing is randomly spazzing your fingers to have a chance to hit all the arrows possible. This is like tossing a dice. That is called luck.