NYPD commissioners use their news conferences at Police Plaza to manipulate the media. Bill Bratton does it better than anyone.

Take his news conference last week, when he described the month of June as having fewer major crimes than any June in two decades. Criminologists and statisticians say a month's snapshot of crime means virtually nothing.

More meaningful is a three- or six-month trend line. Through June 28, the bellwether crime of homicide rose from 145 in the first six months of 2014 to 161 this year, an increase of 11%. The number of shootings went up from 511 to 542, a 6% jump.

Instead, Bratton made the extraordinary claim: "It's my expectation that we may end the year with the, once again, the lowest amount of crime records in the history of the city."

To Bratton, that history apparently began in 1994, when he first became police commissioner. He termed predecessor Ray Kelly's pilot community policing "social work," and began the crime-statistical CompStat program and "broken windows" policing.

Since then, some reporters have been so mesmerized by his crime-reduction claims, as they were by those of his archrival, Kelly, that they appeared confused when reporting last month's low numbers.

The Wall Street Journal described June as the lowest crime month "since the department began keeping detailed numbers in 1994." The AP used the phrase "since similar record-keeping began in 1994."

The New York Times said the June figure was "a low unseen since such records became reliable and consistent in 1993." That happened to be the first full year Kelly served his first tour as commissioner.

In fact, no one has satisfactorily explained what, if any, significant crime-reporting changes occurred in those years.

At his news conference last week, Bratton implied that Kelly had created the tensions between the department and black New Yorkers in his second tour. He announced that he was discontinuing Kelly's signature program, Operation Impact, which placed new recruits in crime hot spots as a show of force.

Instead, he said that most of the additional 1,297 NYPD officers the city has agreed to hire will be part of a plan "to implement a lot of the community relations-building initiatives."