One comment on the video went:
At a very early point in his career, Evans decided he didn't like the tone of his own playing, so he recused himself from the scene for a year and did nothing but work on his tone. That is where the profundity, the sense of space and the unparalleled clarity and sensitivity come from. That is why he can break your heart in less than twelve measures flat.
I don't know if that's factual but it makes a whole lot of sense.