"They are going back to what was already working," he said. "But it was at the expense of the cohort of those students who spent three years in the gap while they were experimenting."
Alonso said the idea that he was responsible for others' test scores was "nonsense." The progress made during his tenure — such a doubling of the number of students scoring advanced on reading tests over the last five years — cannot be downplayed.
Alonso also ordered an analysis of students' raw test scores, which he said shows that "kids might be missing the proficiency mark, but they're still moving." For example, in every grade, among students who didn't pass math and reading tests, scores improved from 2007 to 2012 — even though they didn't become proficient.
Some say the system's stall reflects a constant churn in leadership under Alonso.
Gittings said 85 percent of principals were forced out by Alonso, leaving the system with a deficit of experience, and a lack of leadership in the toughest schools.
Although national research shows that principal turnover can hurt student achievement, Alonso called it a "myth" in Baltimore. He produced data showing that on middle school math tests, principals with one year of experience posted larger gains than those with six or more years of experience.
A recent report on Baltimore said that the foundation of the system's reforms — accountability and autonomy — have been implemented inconsistently.
While Baltimore was identified as a model for cities attempting similar school reforms, Sarah Yatsko, who researched the district for the Center on Reinventing Public Education, said the system still has kinks to work out before results are seen.
"For Baltimore, autonomy has been the Achilles heel — it's been the toughest thing to implement," she said. "When it comes to the nuts and bolts of running a school, the messaging is very confusing across the district."
Although levels of poverty have not been held up as excuses for poor achievement in recent years, several experts said they cannot be ignored.
Abell Foundation president Robert Embry said the backgrounds of students may be an important factor in the plateau in test scores.
He noted that studies have shown that a major factor in how well students do is the income and education of their parents, and whom they share a classroom with. Low-income students in classes with students of higher socio-economic level generally do better.
"We have tougher kids to teach," Embry said. "As our students have gotten poorer, the challenge has gotten greater."
Shiller also suggested that the city's political leaders need to work with the school system to tackle issues that impact students and their parents, such as poverty and jobs.
Having test scores level off for several years is not unusual in cities nationwide, other experts say.
Jack Jennings, former president of the Center on Education Policy, said test scores tend to stall once teachers have gotten initial gains from implementing a curriculum that matches the state's and sets students up to do better on statewide tests.
"In a way it is the low-hanging fruit, it is the easy part. But then it gets harder," he said. "It doesn't mean it can't be done. It is like a never-ending struggle."
Melanie Hood-Wilson, a city schools parent, said the scores could reflect recent school evaluations, which showed substantial deficiencies in instruction.
"We, as parents, place too much emphasis on test scores and too little on understanding what quality teaching is and what a well-run school looks like," she said. "We, as parents, have to set the bar higher and make our expectations clear to our schools, our principals, and our teachers."
Tests scores in city school
•In 2003, 42 percent of third-graders passed the statewide math test. That rose to 78 percent in 2009 but dropped to 74 percent this year.
•In 2003, 44 percent of fifth-graders passed the reading tests. That rose to 82 percent in 2009 but dropped to 76 percent this year.
•In 2003, 31 percent of fifth-graders passed the math test. That rose to 75 percent in 2009 but dropped to 70 percent this year.