A very large number of Norhteastern students (prob. 20-30% for CS, even more for business) are international students, who do not need to submit SAT scores. In fact, Northeastern does not consider their SAT scores even if they do submit them. That’s their way of maintaining very high test score averages while at the same time getting enough revenue (even internationals who get aid end up paying more than nationals.)
So while Northeastern’s student body is impressive and has improved significantly in the last few years, I’d argue the numbers they report are not necessarily the whole truth.