By Meredith Perri/DFP StaffAlready in a 2-0 hole during the second half of the middle frame, the Boston University men’s hockey team found itself with another disadvantage. As freshman defenseman Doyle Somerby skated off the ice with a game misconduct, the Terriers would need to kill off a five-minute major penalty and deal with losing a defenseman from an already thin lineup.As the minutes ticked away, the Terriers (8-15-3, 3-8-2 Hockey East) displayed one of their most impressive penalty kills of the season. Those five minutes of strong play, however, meant little as the Terriers could not overcome an early deficit during Monday’s 3-1 Beanpot opener loss to No. 2 Boston College at TD Garden.“Boy, I can’t tell you how proud I am of our players,” said BU coach David Quinn. “We competed from the drop of the puck until the whistle blew.