Last time I checked, alumni don't *just* stay in the state in which they obtained their degree. They typically settle elsewhere, and there happens to be a lot of B1G alumni in D.C. and Baltimore.
Plus, there have been multiple stories about how New York City has a significant audience for college football in general--if you can get them watching Nebraska, Ohio State, or Michigan via Rutgers (or before, Syracuse, when they were rumored), then adding the woefully under-performing local school in Rutgers pays off.
Also, Fox Sports
supposedly buying the YES! network in New York may play into this as well. (link goes to Frank the Tank page where someone brought this up)
Don't forget that Fox Sports is also the minority owner of the BTN.