New York Mayor Bill de Blasio, shown in 2014. (Craig Ruttle/Associated Press)

NEW YORK Mayor Bill de Blasio (D) wasted no time dismantling the education policies of three-term mayor Michael R. Bloomberg (I), and his administration claims schools have improved as a result. Well, jettisoning data-driven accountability, transparency and standards certainly makes it easier to claim success. But children measured by low standards and with inflated grades may not be learning, which undermines any chance they will have for success.

Mr. de Blasio’s approach to education recently came under intense scrutiny with the release of a $400 million plan targeting struggling schools. So low were the goals for improvement (in some cases, the benchmarks were set lower than a school’s current performance) that they were rebuked as “ridiculous” by a top state education official. In the face of that criticism, city education officials said any schools that meet their benchmarks early will have those targets strengthened and, in a shift of policy, Mr. de Blasio this week announced the closure of three failing schools.

Other areas of concern have emerged. A report issued last month by StudentsFirstNY, an advocacy group for charter schools and other school reforms, found rampant grade inflation, with high marks awarded to students unable to pass state tests. A change in promotion policy has led to charges of increased social promotion, with unprepared students passed from grade to grade.

We won’t romanticize the state of New York City schools when Mr. de Blasio took over; big problems endured. But reform by Mr. Bloomberg and his imaginative school chancellor, Joel Klein, had produced increases in graduation rates, an upward trend in test scores and the replacement of failed high schools with better-performing small schools. Particularly noteworthy was the success of charter schools that offered the kind of choice that better-off parents take for granted. Sadly, even that initiative is threatened; a recent report by the Thomas B. Fordham Institute, a think tank, says school choice has suffered since Mr. Bloomberg’s departure from office.

Making the situation even more worrisome is that it is being played out against a backdrop of state retrenchment. Merryl Tisch, chancellor of the state board of regents, who chastised the city for setting low standards and has been a stabilizing force, is leaving, and new board members are seen as favoring anti-reform union interests. New York Gov. Andrew Cuomo (D), stung by successful union efforts to get parents to opt out of critical testing, is expected to roll back progress on teacher evaluations based partly on student achievement. The losers in all of this are students who are trapped in failing schools and saddled with ineffective teachers. That most of them are poor and minorities doesn’t seem to matter to those who profess to be progressive.