BU was locked into the second seed before the game. HC missed the postseason
That is not correct. BU had a chance to finish anywhere from 1st to 3rd. With a win, They had a chance to pass Army and finish first, earning the right to play all of their tournament games at home. Since Army’s game started at the same time as BU’s game with HC, they still had hopes for first place during the entirety of their game with HC. Also BU still had a chance of dropping down to third place and losing the bye in the first round, which is a big deal. So they had a lot to play for.