Unless something changed with regard to the crew (rowing) program (which historically had more mindshare amongst MIT students), it's likely largely random. In Division III sports, you tend to have high variance in performance, since athletics are seldom the top priority of any of the students. It's probably a combination of solid coaching with luck off the field (which athletes the team was able to recruit) and luck on the field.

Next year, the football team will have a recruiting advantage over the crew (rowing) team, and you may see a long-term shift in football performance relative to crew performance. On the other hand, most US high schools have football teams but no crew teams. Incoming MIT students who didn't play on their HS football teams (most of them) perceive they're at less of a disadvantage competing in crew vs. competing in football. At least, these were my perceptions as an MIT freshman almost 2 decades ago.