By Colby Shannon NEFJ Correspondent BROOKLINE — Described as “the greatest win in program history” from Dexter Southfield head coach Casey Day, Saturday’s victory over Choate Rosemary Hall came off a last-minute score and an energy shifting pick-six. Dexter (8-1) topped the storied Choate program 24-20, sending a message to the rest of the NEPSAC. “We’ve played in a lot of big football games, and our guys believe that until...