I feel like this could be due to how they define 'New York Metro'. I see a lot of people (myself included) moving out of New York City proper and moving to much much cheaper areas like New Jersey, Long Island, Westchester County, etc. This is especially true for recent college grads who simply cannot afford to live comfortably in the city while working at an "entry level" job. I feel like many of us in the tech sector forget this since we,overall, have a decent starting salary in our field, and the "First job out of college" is frequently not the first job in the industry. In other industries the your first job will pay not too much over minimum wage, especially if the field isn't competitive.

So while the data may show people leaving New York, it may not tell the whole picture. My own experience shows otherwise, though I am aware that anecdotes are not data. People may be moving out of New York City, but they aren't leaving New York City.