The Sergeants Benevolent Association of the NYPD has written a scathing open letter to the Democratic National Committee, claiming it wouldn't be safe to bring the 2016 party convention to Brooklyn because New York City is lurching back to the days when citizens were afraid to walk the streets.

The rant, signed by union president Edward Mullins, concludes with a plea for candor about what's happening.

Great idea. Here's some candor:

Our crime rates are still tumbling. Homicide and robbery are down about 12 percent this year over the same period last year. Our overall crime rate in 2014 is down 3.6 percent. New York remains one of America's safest cities.

Shootings are up around 13 percent this year. That's an unacceptable problem the NYPD is trying to solve. But it's not clear whether the trend is a statistical uptick or the harbinger of major problems. Crime statistics tend to fluctuate. To think that the age of fear and loathing has returned, based on current evidence, makes no sense.

While the union says squeegee guys, aggressive beggars and hostile buskers have returned to the city's streets and subways under Mayor Bill de Blasio, the truth is, they never left. If the ranks of squeegee men shrank in Rudy Giuliani's mayoralty, their annoying trade survived. As for the costumed buskers near Times Square, their presence multiplied during the Bloomberg administration. The city, meanwhile, is discussing some plausible fixes.

Given that the union is trying to hammer out a contract with de Blasio, its position is all the more baffling.

The mayor has been in office eight months. The union and its membership of 4,700 active NYPD sergeants have been on the job considerably longer. And they want a pay raise. So now they're arguing that the city is worse than it has been in years?

It's lucky for the rank and file that this argument falls apart on its face. The city's renaissance continues with -- so far as we can tell -- random and scattered trouble spots.

There are many ways to negotiate a contract and voice dissatisfaction with the powers that be. Too bad the sergeants union resorted to false and damaging scare tactics.