Oh sure, New York City's a fine place to be...IF YOU WANNA GET MURDERED!!!
Obviously, you did not read the article.
That said, I doubt that much of the decline has to do with fudging of statistics by precinct commanders. Some might have been changed, but keep in mind that the FBI audits all police statistics twice a year. And murder, the barometer for measuring most crime rates, is VERY hard to downgrade.
Some of it might have to do with the improved quality of medical care, but assaults (which includes attempted, and therefore prevented, murder), and therefore shootings, are also down.