It's cultural. A school system can only be effective up to a point, but depends mostly on the stock of students/parents involved in the system.

You'll see MA scores among the top states in most forms of human development, so it shouldn't be surprising that the schools reflect that trend. The MA school system is likely not doing anything particularly unique that will be the antidote to failing systems in other states. It's likely the best way to replicate their success in other states lies in policy not directly related to school systems.