This is buried in the long article on Michelle Rhee

Rhee embodies one extreme in the debate over public education. She believes that every child can achieve, regardless of conditions such as poverty, broken homes, underfunded schools. In her view, the main obstacles are weak teachers, bloated bureaucracies, union contracts. She is driven by data, convinced that learning and teaching can be measured with as much certainty as a dieter tracks progress on a bathroom scale.

Her agenda has provoked aggressive push-back from teachers unions and many progressives, who say that social factors have a profound impact on children and that Rhee’s policies unfairly scapegoat teachers. They say the worship of test data has created a “drill and kill” culture that has narrowed curriculum, sucked the joy out of the classroom and, in extreme cases, resulted in test scandals in Atlanta, the District and elsewhere.

Shouldn't progressives like more data, open to ideas like evaluating teachers. Sticking to "joy of the classroom" looks very old school  !