Mayor Bill de Blasio on Wednesday brushed off evidence of rampant abuse in the home of dead 5-year-old Mikey Guzman as he defended his beleaguered Administration for Children’s Services.

And just a day later, Hizzoner was stone-silent as the Department of Investigation eviscerated ACS for its systemic failures leading up to the death of another child, Jaden Jordan, in Brooklyn.

“DOI’s investigation found that the depth of errors over a two-day period was so significant, and the errors involved the overall implementation of policies so basic, that they go to the heart of ACS’s core mission of protecting children and implicate high-level, systemic problems,” a summary of the report reads.

The DOI is investigating the deaths of more than a half-dozen children who were known to ACS, including Zymere Perkins, a 6-year-old Harlem boy who was bludgeoned to death with a broomstick in September, and Michael “Mikey” Guzman, who was found dead Sunday.

De Blasio was dismissive of the 13 visits by ACS to Mikey’s family — including eight substantiated cases of abuse or neglect — by suggesting there is no proof and that the boy may have died of natural causes.

On Thursday, Hizzoner did not release any public statements about Jaden, nor did he mention him in two media interviews spent railing about President Trump.

De Blasio has routinely deflected criticism of ACS. In December, he allowed Commissioner Gladys Carrion to submit her resignation a week after Jaden’s death rather than fire her for mishandling the case. She remains in charge of the agency while a replacement is sought.

Jaden, 3, was allegedly beaten by his mom’s boyfriend on Nov. 28 — just two days after ACS received an anonymous tip that he was being held in a locked dog crate.

He suffered a fractured skull and died in the hospital on Dec. 4.

“The investigation found that despite ACS having the mandate, resources and information to urgently find Jaden, ACS did not find Jaden before he was allegedly beaten into a coma,” the report says.

ACS said the anonymous tipster gave an incorrect address for Jaden, so its investigators couldn’t find the family. But the DOI probe found that caseworkers actually had access to databases with the information and could have located him sooner.

A major problem is that workers in the agency’s emergency children’s services unit — which handles cases during nights, weekends and holidays — aren’t adequately trained in how to use the databases.

“DOI found there was inadequate staffing, case practice, supervision and training within the unit,” the report states.

“In addition, DOI determined that the ECS unit is governed by policies that are inconsistent, confusing and contradictory.”

ECS staffers told city investigations they couldn’t remember the last time they’d been trained, and supervisors complained about not having enough time to review cases. These issues are particularly problematic because of the “high volume of investigations, 70 percent of which are high-priority,” that ACS receives on nights, weekends and holidays, city investigators said.

“DOI found that poorly trained staff and inadequate staffing in a unit that receives a high proportion of critical cases is a systemic problem,” the report said.

As a result of the probe, the DOI has made a series of recommendations to ACS, including that it report all allegations of criminal conduct to the NYPD immediately and make sure it has adequate staffing.

The child welfare agency has also agreed to form a new unit that’s responsible for conducting database searches.

ACS spokesperson Aja Worthy-Davis said in a statement, “The loss of Jaden Jordan’s life is deeply disturbing. From the time we received an anonymous report with various inaccuracies, to the 48 hours in which when we clarified data and visited the location, vital time was lost.

“We have reviewed and are implementing many of DOI’s recommendations and are disciplining staff who failed to exercise critical thinking in investigating this case,” she added.