Last week we described the Houston Independent School District as barreling down a hill with no sense of direction. Rather than steer us onto a clear course, it looks like our dutiful driver has decided to bail out.

Commitment is the hallmark of great leadership, yet Superintendent Richard Carranza has accepted the position as New York City’s next chancellor of schools, leaving Texas’ largest school district after a mere 18 months on the job.

All too often it feels like our city is used as a stepping stone for ambitious tuft-hunters, but if Mayor Bill de Blasio and others think they’ve scored the next great wunderkind, they should think again. We’d like to say that Carranza’s legacy will be marred by his abrupt departure but that presumes he has a legacy to tarnish.

Carranza leaves behind the chaos of unfinished work. He inherited a tumultuous situation and fed the flames.

While our city welcomed him so recently with joyful mariachi bands, his send-off will be more subdued.

WHAT WE SAID THEN: New Houston schools chief shows strong potential

During his whirlwind tenure, Carranza announced his intent to reverse the district’s longstanding commitment to giving greater authority and responsibility to principals in “site-based” rather than top-down management. He upset nearly everyone with his plans for overhauling the magnet school program and revamping the way schools are funded within the district.

Either to underscore the urgency of his agenda or because of his failure to accurately forecast district revenues, he cited a $200 million budget shortfall, then reduced it by $85 million without a change in circumstances.

That’s an awful lot of spinning tires and squealing gears to accomplish, well, little. His many announced initiatives and about-turns have so confused parents, teachers and principals that some have actually taken the time to delve deeper into the issues than they ever have before. Even so, the superintendent has packed his suitcases without leaving behind a new vision for HISD or much progress in closing the achievement gap.

Admittedly, a big city public school superintendent is one of our nation’s most difficult jobs. Carranza was handicapped by a divided board and an archaic, inadequate system of state school funding. The grandson of Mexican immigrants worked long hours in the aftermath of Hurricane Harvey. Perhaps Carranza thought that his community outreach was laying the groundwork for concrete reforms yet to come. But any community trust built up isn’t likely to bear fruit given how quickly he was willing to pull up stakes for a more prestigious offer.

EDITORIAL: HISD moving too fast, and in the wrong direction

Houston once took pride in our ability to elect a board that retained the confidence of taxpayers, but now HISD’s politicized school board and lack of clear direction strengthen the hand of those who argue that large, diverse school districts are ungovernable and averse to the type of innovation observed in high-performance charter schools.

The superintendent — who often seems to bend to the will of the loudest trustees — has done little to heal the divisions on the board. Further, we have to wonder how HISD will counter the threat of more centralized controls from Austin when the school district itself has floated its intention of taking back the authority that it once gave to principals.

HISD trustees must face the fact that Carranza’s departure for the Big Apple only aims the district squarely in the direction of a state takeover. Superintendent turnover is a classic symptom of an irreparably dysfunctional board, and the Texas Education Agency has already put the district on red alert because of several failing schools.

Carranza wasn’t de Blasio’s first choice. Last week, de Blasio announced that he had hired Miami’s popular and effective superintendent, but he was left in the lurch when that superintendent decided to stay put after being deluged with public support for those who wanted him to stay in Miami.

De Blasio does not need to worry about that outcome in Houston.

But New Yorkers should wonder about the endurance of their new hire, who left the nation’s seventh-largest school district with a mess on its hands, partly of his own making.

For the sake of New York’s 1.1 million students, we hope that the new chancellor of New York City public schools, an accomplished mariachi singer, sticks around long enough to sing an uplifting ballad rather than merely cacophonous noise.