I once edited a friend's draft and reduced the word count by almost 1/3. I didn't change a damn thing. All I did was remove unnecessary words like to, that, and very. I did more than that, obviously, for such a big reduction in word count, but it was all the same idea.

When I was finished, my friend said, "I can tell you did things, but I'm not sure what. It looks the same, only better."

Sure, because I got rid of the unnecessary words in his draft! People might not be able to put their finger on why a piece of writing is better because it has fewer words, but they know, intuitively.