Barnett, a professional city manager who held top jobs in Austin, Texas, and Washington, D.C., was struck by tragedy before she started the job. Her husband was killed in a car accident on Interstate-95 in January 2008, as he was transporting some of their belongings from Washington to Philadelphia.
Nutter said no replacement has been selected. He praised Barnett's service to the city, noting her work in establishing the 3-1-1 non-emergency call line and the PhillyStat data-collection system.
But Barnett never quite found her footing in a government that downsized her typically powerful job. Unlike previous managing directors, Barnett didn't ride on trash trucks, stop at fires, manage traffic disasters or hold news conferences.
"I think it's clear her role and the structure of the office was certainly different from the last several years," said Phil Goldsmith, managing director under Mayor John Street.
Administration sources said Barnett's authority and scope were curtailed by an administrative structure that gave many of the managing director's traditional powers to the deputy mayors, who report to both Barnett and Nutter.
For example, when the city managed a massive parade in honor of the World Series-winning Phillies, the deputy mayor for transportation and public utilities, Rina Cutler, took media questions on the post-parade cleanup. During the controversial attempt to close city libraries, the deputy mayor for health and opportunity, Don Schwartz, was out front.
And sometimes the mayor himself took the spotlight - as evidenced by Nutter's starring public role in the city's recent snow-fighting efforts.
Barnett and Nutter defended the administration structure.
"The way the administration is organized is a very typical way for a large organization," Barnett said. "I had enough to do, I had enough power to do it."
Barnett also took flak for some of her less conventional management decisions - like bringing her dogs to work and asking her staff to help care for them.
Barnett, whose last job was with Philadelphia-based Public Financial Management in its Washington office, left her last two public jobs under difficult circumstances.
In Austin, where she served as the city's top manager, she left after it was discovered that a city-owned hospital for which she was responsible was running a $21 million deficit.
And in Washington, she resigned as chief management officer after only a year, under criticism that she hadn't improved services rapidly enough.