I've been lurking for a couple of years now.. time for me to chime in again:
This makes absolutely zero sense and is a total waste of space.
There should be classrooms or other university use directly below the field, with garage space down lower.
The building(s) being torn down are these giant 1920's era storage sheds. Once used as warehouses, they were bought by BU at some point and used by the ROTC for training and the marching bands for practice. Not a huge loss here.
What is really needed in this area is more housing, not sports garbage.