Former police Commissioner Ray Kelly has, without any substantiation, accused successor Bill Bratton of massaging crime statistics to make the city appear safer than it is. At 1 Police Plaza, officials don’t lack possible reasons for Kelly’s claim:

- He’s hoping to sell his book, “Vigilance,” which isn’t doing so well.

- He’s seeking attention after separating from the commercial real estate powerhouse, Cushman & Wakefield, and hooking up with the smaller K2 Intelligence security firm.

- He’s testing the waters for a mayoral run.

Kelly seems to have acted from his inability to recognize that it’s been two years since he left a job he held for 12 years.

Bratton has called on Kelly to “be a big man” and identify his sources for his undocumented claim. Police officials say Bratton’s use of the word “big” is especially pointed, given Kelly’s sensitivity to his 5-foot, 8-inch frame.

Fudging crime figures is as common in policing as doping is in sports. The NYPD’s former internal affairs chief, John Guido, warned about it when Bratton began his CompStat program in 1994 under Mayor Rudy Giuliani. He said commanders would be tempted to cheat because their promotions were based on crime-reduction results.

Bratton vs. Kelly has been in play for 25 years, settling personal scores through police policies. In the 1990s, as head of Transit Police, Bratton nearly persuaded Mayor David Dinkins to pass over Kelly, then first deputy, and appoint Bratton commissioner. Dinkins went with Kelly, who resuscitated the NYPD, eased racial tensions and even inaugurated a small crime drop.

But as mayor, Giuliani wanted a break with the past, and appointed Bratton. As crime fell, Bratton and Giuliani disparaged Kelly’s accomplishments. Most galling to Kelly was that they took credit for his removal of the squeegee men and that they called Kelly’s community policing policy “social work.” Sworn in as commissioner in the wake of 9/ll, Kelly set off stop-and-frisk.

Returning as commissioner under Mayor Bill de Blasio, Bratton overhauled Kelly’s signature policy. He also signaled a change to Kelly’s counterterrorism policy, promising to collaborate with other law enforcement agencies, in particular the FBI. Kelly had gone “lone wolf” for 12 years.