There’s a natural tendency for new executives to blame their slow start on the job on the old guy and for the previous occupant of the throne to complain that the new guy is dropping the ball, so it’s not surprising that Adams and de Blasio are sniping at each other. But in this case, Adams — and by extension all New Yorkers — has legitimate grievances to air regarding how de Blasio mismanaged the city, down to his final days in Gracie Mansion.

And as for Bill … well, he has a lot of explaining to do.

Twenty months into the pandemic, New Yorkers were looking ahead to the reopening of our city and hoping to pull together the shattered fragments of our civic life. But in December 2021, with just a few weeks left in his term, de Blasio expanded vaccine mandates for private-sector workers.

“We’re going to announce a first-in-the-nation measure,” he bragged on “Morning Joe,” forcing private businesses — comprising 90% of the city’s workforce — to make sure their workers were vaxxed and maintain records regarding their vaccination status. This mandate, of uncertain legality, confounded and enraged private employers, who were (and still are) struggling to return to normal. In its nine months of existence, the private mandate was never widely enforced, but it wasn’t ever meant to be: It was just a classic de Blasio parting shot to demonstrate his love of bold, meaningless gestures that embody his beloved principle that government can, and should, do anything.

Along a similar line, in his last year de Blasio established a “Racial Justice Commission,” modeled on South Africa’s “Truth and Reconciliation Commission.” The mayor specifically compared post-apartheid South Africa with New York City, predicting the RJC would “begin to dismantle structural racism for all New Yorkers.” The Racial Justice Commission drafted city charter revisions, which were voted on and passed in the last election, establishing an “Office of Racial Equity,” led by a “Chief Equity Officer” to work toward “advancing racial justice and equity” in New York.

This is all classic de Blasio blather. It forces every city agency to hire a new layer of commissars to promote a political agenda while doing nothing substantive about the “structural racism” that supposedly infects the city.

It’s hard to look back at de Blasio’s final actions on Rikers Island — two weeks before his term ended — as anything but a malicious effort to sabotage his successor. In mid-December 2021, de Blasio began a mass transfer of inmates in punitive segregation — put in solitary confinement because of their violent attacks on jailhouse staff — back into general population.

Clearly a poke at the corrections-officers union, de Blasio’s move, also dressed up as an “equity” gesture, contributed to the rise in violence at the jail complex.

On schools, de Blasio — again in his last days in office — announced a plan to get rid of academic screens and gifted and talented programs, then let Adams deal with the backlash.

But these incidents — little stink bombs meant to annoy the incoming mayor — are nothing compared to the primary project of the entire de Blasio administration, which was to systemically deconstruct the city’s apparatus of public safety. In 2014, de Blasio dropped the city’s appeal of the poorly judged stop-and-frisk case, agreeing against all reason or evidence that the NYPD had behaved unconstitutionally in getting guns off the street.

De Blasio signed legislation decriminalizing a broad range of quality-of-life violations, ensuring the city would get smellier, dirtier and less safe. He worked overtime to flip the state Senate, enabling the passage of bail reform. And he backed the absurd plan to close Rikers and build local borough-based jails, which is a thin ruse to put a hard cap on the number of people who can ever be detained, ensuring the city will never have enough room to detain dangerous criminals.

It’s no wonder that Eric Adams is frustrated. The only question is why more New Yorkers aren’t angry at Bill de Blasio, too.