Just a note that this is Northeastern (in Boston) not Northwestern (in Illinois). Northwestern was and is typically a very high ranker.
As for what the improvements are like... hard to say. Some ways to improve the rankings like getting more students you don't want to come to apply (so you can appear more selective) don't actually help at all, while things like small classes even if done to "game" the rankings could actually help.
There's also just the cyclical aspect of things: the quality of your experience is going to be significantly determined by the quality of the student body, so if you have a better applicant pool because of your better rankings you maybe have a bit of a virtuous cycle that's somewhat disconnected from whether the things you changed actually improved anything real on their own other than the ranking.
As for what the improvements are like... hard to say. Some ways to improve the rankings like getting more students you don't want to come to apply (so you can appear more selective) don't actually help at all, while things like small classes even if done to "game" the rankings could actually help.
There's also just the cyclical aspect of things: the quality of your experience is going to be significantly determined by the quality of the student body, so if you have a better applicant pool because of your better rankings you maybe have a bit of a virtuous cycle that's somewhat disconnected from whether the things you changed actually improved anything real on their own other than the ranking.