Scientific realism is an approach that holds that researchers must study interventions along with the contexts in which they occur. In other words, researchers who are trying to come up with a way to reduce levels of crime should not simply take one strategy and try to apply it to all crimes in all places. Instead, they need to tailor their strategies to specific contexts. They need to study how various interventions work in those different contexts.
The Boston Gun Project was a good example of this because it focused intensively on one particular context. It looked only at one community and tried to find methods for reducing homicides among young people in that community. By intensively researching that community, the researchers were able to understand the community and the nature of its particular kind of gang violence. They were then able to design interventions that worked there, even though those same interventions did not work in other cities.
Because of this small-scale, case study approach, this is a good example of the scientific realist approach.