Deputy Superintendent Michael Goar, the second in command in the Boston public schools, announced his resignation on Wednesday, the latest in a series of high-level departures that have left notable gaps in the superintendent’s leadership team.
Goar’s exit is surprising, given his position as one of Superintendent Carol R. Johnson’s closest and most loyal advisers. He came to Boston just a few months after Johnson became superintendent in 2007, and he previously worked for her while she oversaw school systems in Memphis and Minneapolis.
The exodus of so many high-ranking officials — at least eight since June — presents a significant challenge for Johnson as she oversees a series of important initiatives, most notably overhauling the city’s system for assigning students to schools and rolling out a new evaluation system for teachers and principals.
It also comes as Johnson is attempting to shake up her leadership team, after a series of scandals this summer raised questions about her own leadership and a potential breakdown in communication up and down the ranks.
She said most departures reflect a competitive market for school administrators nationally — noting that some administrators decided to move back to their home states to be closer to family — and that others simply retired.
Some of the recently vacated positions include the chief academic officer, the academic superintendent for high schools, the academic superintendent for middle and K-8 schools, the executive director for special education and student services, and the chief accountability officer.
The positions are unfilled or are covered by temporary appointments until Johnson decides on the structure of her new leadership team.
“Because we have highly talented people, we shouldn’t be surprised they are recruited and sought after,” Johnson said in an interview last week. “We work hard to hold onto them and try to encourage them to stay in Boston. But I personally try not to get in the way of people who want to have different professional opportunities to learn and grow.’’
Close observers of the School Department have been wondering what the departures mean for the future of Johnson’s tenure and initiatives to bolster school quality.
“The turnover at the top of the superintendent’s team is an alarming development,” said Richard Stutman, president of the Boston Teachers Union, which recently wrapped up tense negotiations over a new contract. “There doesn’t appear to be an end in sight, and there doesn’t seem to be a bullpen.”
Samuel Tyler, president of the Boston Municipal Research Bureau, a government watchdog funded by nonprofits and businesses, said, “I think it is probably a combination of some administrators not being in sync with the superintendent’s style and some where it is based on their performance, or it was time to move on.”
Goar, who played an instrumental role in negotiating the teachers’ contract and developing five proposals to overhaul the student-assignment system, is one executive that Johnson did not want to leave. She convinced him this summer to turn down offers from Georgia and Texas.
But Goar said the most recent job offer was too enticing: Returning to Minneapolis, where he originally moved at the age of 10 from Korea, to become the executive director of Twin Cities STRIVE, a nonprofit that advocates for high-quality public education.
‘Because we have highly talented people, we shouldn’t be surprised they are recruited,’ Carol R. Johnson said.
“I’m saddened to leave my superintendent here,” Goar said, calling Johnson his mentor. “I’m always inspired by her leadership and am in awe of her capacity to teach me things.”
He said that as he decided whether to leave “there were a lot of difficult conversations I had with the superintendent.”
Johnson announced Goar’s departure, slated for early October, in a letter Wednesday to staff and the community.
“While we would have liked Michael to stay with us for many years to come, he has made this decision for a variety of reasons, and we wish him all the best in his new endeavor,” Johnson wrote.
While Johnson praised Goar’s work during his five years in Boston, he also has been at the center of some of the School Department’s most heated public battles. For instance, he oversaw efforts to fix the problem of late school buses that blemished the past two school years, and a facilities proposal that underestimated the costs of relocating several schools this year by millions of dollars.
Goar, who makes $177,000 a year, is the third high-ranking official to announce a departure at the start of this school year, an unusual time to bow out.
Domenic Amara, academic superintendent for K-8 and middle schools, retired on Sept. 7, and Linda Cabral, the academic superintendent for high schools, will retire on Sept. 30. Their retirements come amid high-profile investigations into three schools they supervised that exposed a potential breakdown in oversight in the superintendent’s office.
For Cabral, it was the case of Rodney Peterson, former headmaster at the O’Bryant School of Math & Science, who excessively used sick time and collected pay on a day he was arraigned on a charge of assaulting his wife.
For Amara, the cases revolve around the School Department’s handling of allegations that a teacher at the Kilmer K-8 School had inappropriate contact with a student and an investigation into the misuse of funds and technology at the Frederick Pilot Middle School , where the principal has been placed on leave.
Johnson would not say whether the retirements of Cabral and Amara were related to the incidents at their schools.
“I think decisions like this are usually more complex than a single incident,” said Johnson, noting Amara worked for the School Department for nearly 50 years and Cabral for more than three decades.
One of the most perplexing departures was that of Cynthia Hays, who abruptly quit in June as chief academic officer after less than a year on the job.
She was at least the fourth person to hold the powerful position, which oversees all aspects of student learning, during Johnson’s five-year tenure.
In a letter in response to Globe questions, Hays did not specify why she left but noted that externally driven initiatives side-tracked her and Johnson’s efforts to execute a long-term plan to boost student achievement.
“I witnessed the superintendent being constantly bombarded with innumerable externally driven, competing priorities demanding her attention and her time,” Hays wrote on Aug. 3. “She is a ‘hands-on’ superintendent who is intimately involved in every aspect of the school district’s operation. This means her expertise and time must be protected.”
The Rev. Gregory Groover, the School Committee’s chairman, said he is confident that Johnson would pull together a top-notch team.
“I know she is working on a transition and working on filling those positions,” Groover said.James Vaznis can be reached at email@example.com. Follow him on Twitter @globevaznis.