In my city, there are 5 high schools in different parts of the city. There is a huge difference between the rankings of 2 schools compared to the remaining three. Funding and teacher pool are pretty much the same source. The main difference is the students and their families. The parents in those areas are well educated and have high income. If anything the best performing schools looks like a dump compared to the 3 lower performing ones. I'd say student background plays a huge part on their performance.