As superintendent of San Diego Unified, Cindy Marten faces a political balancing act, a delicate dance to appease four sometimes opposing forces: parents, the teachers union, city leaders and the school board.

Tangle with any one of them, and her vision for the school district is jeopardized.

“Very few jobs face that type of pressure — political upheaval, scrutiny from media and the public, neighborhoods fractured by race and language, operational challenges,” said Mike Casserly, executive director of the urban public-school advocates Council of the Great City Schools.

“And that’s all within the context of the community wanting improved student outcomes.”

This also might say something about the turnover rate for superintendents in large urban districts. Nationally, the average tenure for these positions is just under four years.

San Diego Unified has had five superintendents in the past 10 years — more if you count interim leaders.

That’s not a good thing. “Having a superintendent for a long time doesn’t guarantee that you’ll get long-term gains in student outcomes,” Casserly said, “but the converse of that is a recipe for failure.”

Every time a new superintendent comes in, he or she brings a new vision, a new agenda and new courses of action for reform. There’s lost momentum — it’s like starting over.

It’s easy to retrospectively point out areas where the last four superintendents fell short, and where they succeeded. It’s much more difficult to take each lesson and apply it to the current state of the district.

But that’s the task at hand for Marten. In a sense, the ghosts of superintendents past are still hanging around, informing today’s decisions. Here are some lessons we can take from their legacies.

Alan Bersin (1998-2005)

Lesson:  Push too much, too soon and something’s gonna break.

Out of all the district’s ghosts, Alan Bersin’s might be the noisiest. A backlash against the top-down reforms he pushed continued to shape school reform long after his departure. Ever since, the district has been wary of quick, dramatic shifts.

Terry Grier, a successor, once joked that he felt like Bersin lived in the closet.

Bersin so ruffled feathers that a few school board members compared him to Hitler.

Education historian Diane Ravitch told VOSD in 2010 that Bersin’s problem was more style than substance.

Ravitch, once a vocal proponent of No Child Left Behind, pointed to Bersin as an example of how top-down mandates and frequent testing doesn’t create lasting improvement.

San Diego teachers union president Bill Freeman said Bersin’s flaws were more than stylistic. He said the superintendent unrealistically expected all teachers to teach the same things at the same time.

“Kids learn at different rates,” he said. “We have to differentiate the learning. The only person who wouldn’t understand that is someone who didn’t have children or had only one child,” Freeman said.

Tad Parzen at one point served as Bersin’s general counsel and is well aware of the narrative that surrounds the former superintendent.

But he said much of the criticism overlooks the positive changes Bersin made — such as his deep focus on literacy and his eagerness to use data as a guide to understanding progress.

“Bersin’s motivations came from the right place. He always said that it wasn’t his job to be popular. It was his job to improve student outcomes,” Parzen said.

By 2005, a year before his contract expired, even Bersin loyalists agreed that the rancor he stirred had become a distraction. The district paid $240,000 to settle his contract, and told him to kick rocks. Many of his reforms were quickly dismantled.

Bersin moved on to the Department of Homeland Security, and was appointed by President Obama in 2010 to serve as Border Czar. He’s since been promoted within the department.

Carl Cohn (2005-2007)

Lesson: Play nice with the school board.

Maybe because of his hands-off leadership style, maybe because Bersin’s reputation looms so large it has its own gravitational pull, Carl Cohn’s legacy is largely faded and distant.

After a successful tenure at Long Beach Unified, Cohn was lured out of retirement by a $250,000-a-year contract at San Diego Unified. By 2007, a year and a half before the contract expired, he was gone.

In the beginning, Cohn seemed like the perfect fit. For starters, he wasn’t Bersin.

Cohn promised to lead more diplomatically than Bersin, but he liked many reforms that his predecessor left behind. He was on board with his Bersin’s early focus on literacy, for example.

Also with Cohn from the start, however, were whispers of tensions that would become his undoing.

In a 2005 interview with the San Diego Union-Tribune, Cohn called the San Diego Unified school board “squirrelly” and questioned its willingness to unanimously move forward on major reforms.

“The forces of the status quo in an urban school district are legion,” he said at the time.

As if he predicted it, discord between Cohn and trustees eventually flared. He accused the board of micromanaging, and in the process, violating the no-meddling clause that was written into his contract.

In 2007, after the school board voted down his budget just days before the state’s deadline, Cohn called it quits. School board members were left searching for common ground as well as a new leader.

Terry Grier (2008-2009)

The lesson: You mess with the union, you get the horns.

After a nationwide search, the district found Cohn’s replacement in North Carolina.

Terry Grier blazed into San Diego with a bold mission: Rapidly improve reading proficiency levels; narrow the achievement gap; streamline administration.

He didn’t last long.

The district was still skittish of sudden movements, which frustrated Grier. In an interview with KPBS, he said the district was passing on reforms simply because they were initiated by his predecessor:  “I’ve said this every day I’ve been here — it’s as if I’m still living with the Alan Bersin ghost.”

Grier walked into a financial mess. When he arrived in spring 2008, the district was bracing for an $80 million budget cut. Grier cut 350 central office positions, but quickly drew flak from the union when he suggested additional teacher layoffs.

“It’s very simple to say, ‘Don’t lay off anyone.’ But what happens when you don’t lay off anyone?” he told VOSD at the time. “If we have an $80 million deficit, how would you suggest that we recoup that?”

The gulf between Grier and the teacher’s union only widened. Freeman said that Grier didn’t care for the union contract, and as a result the two parties communicated poorly.

“He wanted to dictate to educators what they taught. He wanted to lay off teachers, unnecessarily,” Freeman said. “He would say that he didn’t have the money to pay teachers, but when we looked at the budget the money was there.”

The union, still salty about the nearly 1,000 layoff warnings sent to teachers the previous spring, threw more than $388,000 at November school board elections.

It worked. The arrival of John Lee Evans, along with Richard Barrera and incumbent Shelia Jackson, established a new, union-backed majority on the board.

And so, when Houston called Grier to offer him a fat contract and the ability reward teachers whose students’ test scores improved the most, he answered.

After only a year and a half in San Diego, Grier was on his way to Texas.

Members of the business community tried to woo Grier back.  But it was too little, too late.

Bill Kowba: (2010 - 2013)

The lesson:  “Nice” gets the job done, but it doesn’t inspire.

It’s difficult to find someone who has a harsh word to say about Bill Kowba. He was a master administrator, people say. He cared deeply about kids and wanted to see them succeed.

He was also the right person at the right time, Parzen said.

In 2010, VOSD dubbed him the “accidental superintendent.” After all, he’d twice stepped in as interim superintendent and was virtually guaranteed the job even before his contract was drafted.

But as tough as is it to find an outspoken critic of Kowba, it’s just as challenging to find someone who was dazzled.

Kowba’s strength was administration — not education. Early in his tenure, educators worried that he’d tiptoe around the school board and that his instructional reforms would take a backseat to his focus on the bottom line.

Despite lacking a background in education, standardized test scores slowly rose during his tenure.

Kowba also helped decentralize the district, giving each school the ability to craft its own reforms instead of waiting for top-down mandates. Area-superintendents would lead schools within their designated geographic area.

The plan, which critics feared could harm district cohesion, is still intact today. And Marten has no plans for dismantling it.

Last February, Kowba announced his plans to retire at the end of his three-year contract. He left on good terms with the school board. That’s fitting — he never tried to challenge their authority, or strike out on his own.

So, What Makes Marten Different?

A lot, actually.

Unlike Bersin, Marten praises teamwork, and has said repeatedly that data and test scores should be used as a guide instead of a goal.

In contrast to Cohn, she’s well supported by school board members. The board essentially handed Marten a plan when she started, so she didn’t have to worry about getting others to buy in.

Where Grier fought with union leaders, Marten gets along. Where Kowba fell quiet, Marten’s rhetorical flair can inspire change.

Unlike any of them, she never applied for the job. In fact, she was selected in a controversial process ­— the board unanimously chose her without a formal search or public forum.

Marten said she had qualms about the selection process at first, but that it ultimately points to her motivation.

“I’m not here for the job title. I’m here for the work.” said Marten, adding that she’d be just as happy teaching or serving as principal. “I’m here because I was asked to be here and I believe I have something relevant I can offer.”

Marten doesn’t promise fast change. Ask her how long it will take to revamp the district, and you’ll get a straight answer: “Eight years,” she said. “Our success is not going to happen overnight.”

Casserly said that it’s rare for so many forces to come together favorably, as they have for Marten. “And the longer that’s sustained, the better her chances of success,” he said.

For the moment, the stars are aligned for Marten. But it all could change.

Next year, two school board members, Kevin Beiser and Scott Barnett, will be up for re-election. Depending on the outcome, Marten could face a split board.

The spring will bring a new mayor, and the dynamics between the district and the mayor could change depending on who takes office.

Freeman is stepping down from his presidency, just as contract negotiations between the district and union will be coming to a head.

The degree to which any of these changes will actually matter for Marten, is still a matter of speculation.

But what it means to Lisa Berlanga, executive director of the parent advocacy group UPforEd, is that Marten has a window of time where everything is on her side, and that she’d do well to push for policy reforms – like having principals in classrooms more often – before the honeymoon is over.

“Basically if there is anything she wants modified, changed, now is the time,” she said. “It’s going to be interesting to see if Marten can push hard enough to make changes without pushing too hard and ruffling feathers.”

Correction: An earlier version of this post said that there have been five superintendents in the past five years. There have actually been five superintendents in the past 10 years.