If you look at the best times run by the B.U. athletes themselves you will find that in most cases their outdoor times are faster than their indoor times or have been achieved at sites other than B.U..
For example, Rich Peters ran a 3:56 mile at B.U. last year, but outdoors ran 3:37 for 1500. Katie Matthews ran 9:07 for 3k and 15:46 last year at B.U., but ran 9:05 for 3k at the University of Washington and 15:42 at Fayetteville. Tewado Latty ran 46.86 at B.U. indoors, but ran 46.18 outdoors, Page ran 21.25 indoors, but 21.07 outdoors (hamstring problem).
The straightaways on indoor tracks are less than 40 meters, so for every lap run, 120 meters of it are on a curve. People cannot run as fast or efficiently around a curve than they can on a straightaway. Hence, the explanation for why even B.U. runners run faster outdoors than indoors.