Philly looking to reverse privatization-- why?

A report from the Washington Post's Keith Richburg (hat tip: C-J)...

Six years ago, the Philadelphia School District embarked on what was considered the country's boldest education privatization experiment, putting 38 schools under private management to see if the free market could educate children more efficiently than the government....

This month [in June], the experiment suffered a severe setback, as the state commission overseeing Philadelphia's schools voted to take back control of six of the privatized schools, while warning 20 others that they had a year to show progress or they, too, would revert to district control.

Students at Philadelphia's schools have made improvements overall, the commission said. But the private-run schools are not doing any better than the schools remaining under public control....

Uhh...why is it a failure if the quality is the same-- and this is cheaper and provides more choice?!