Will Shortz has been the New York Times crossword editor for almost twenty years. He explained to Alex Hoyt how he goes about editing the puzzles.
Every crossword in the Times is a collaboration between the puzzle-maker and the puzzle editor. On average, about half the clues are mine. I may edit as few as five or ten percent of the clues, or as many as 95 percent for someone who does a great puzzle but not great clues. Why accept a puzzle when I’m going to edit 95 percent of the clues? Well, if someone sends me a great puzzle with an excellent theme and construction, you want fresh, interesting, familiar vocabulary throughout the grid, I feel it would be a shame to reject it on account of the clues, because I can always change them myself.