There are lots of reasons given for why a school is so good--the administration likes to credit their work and the work of the teachers. And, while I won't discredit them, the real reason is the neighborhood the school is in and the type of kids the school admits.
Let's face it, a school in a middle class neighborhood, with feeder schools filled with kids that will attend it gives it a good start. Parents don't have to worry about kids traveling long distances on public transportation. Because of these good kids, the school offers many programs aimed at the better students and good kids apply and get admittance. You see the high school admissions policy is not totally random. Administrators and counselors go over applications with a fine tooth comb and take the best of the best. A child with "3's" on middle school exams doesn't stand the same chance of getting in as a child with "4's" and the kid with "1's" and "2's" is totally dependant of the luck of the draw.
Years ago I taught at one of the most difficult schools in the city. In fact, this school was one of the first ones to be closed down for reorganization. Everyone knew then it wasn't because the teachers were no good. All these teachers were able to find new jobs in the schools they wanted to be in. Many went on to teach advanced placement classes and become mentors and administrators. The school closed because the school population consisted of some of the roughest kids in the city. Back doors were always being propped open so intruders walked in all the time. Halls weren't safe and classes had to be taught with locked doors to insure the safety of the teacher and the students inside. Kids came in with no skills. One of my students was found with a sawed off shotgun. Another shot an FBI agent. I'll never forget Sheldon, who used to go down to the docks and help the longshoremen unload boxes, by unloading many for his own personal use. Fires were always started during fire drills (the kids wanted the drill to be realistic, I guess.) I taught kids who couldn't count past 100 and couldn't read more than Dick and Jane. I taught kids who lived in burnt out buildings with no heat or hot water. And, while we gave our all, coming in early, staying late to help, there were terms we couldn't get anyone to pass the regents. (Of course it was a real regents in those days.) No one, not ever blamed the teachers.
I recently read a memo by a Principal of a good school. This Principal was proud of all the school had done and was thrilled that people from the state were coming to see what was being done there. I know the school is good and the people who work there, including most of the administration, do a good job but, change the neighborhood, change the kids who feed in and I guarantee this same school with the same practices and the same staff will be on Bloomberg's list of schools to close. The same teachers will be ATRs as no school will want to hire them.