Music is a means of communicating. What it communicates is not reducible to words, but it is like a language.Understanding a piece is understanding what it is expressing (and, in performance, communicating that via one's playing to a listener).Dynamics are part of the means of communication, but are not the same as understanding what one is trying to communicate.By way of analogy, I (who do not speak the language) could learn a speech in Mandarin. I could learn patterns of stress and emphasis. But without understanding what I am trying to say, it will always sound false - not quite right - partly because I am bound to make subtle errors, but moreso because I am not actually communicating anything of my own.
I appreciate this post.