Exelby, 30, spent last season in the Detroit Red Wings' system playing for the Grand Rapids Griffins in the AHL. He had seven goals, 14 assists and 177 penalty minutes in 75 games. He has played 408 NHL games with the Atlanta Thrashers and Toronto Maple Leafs.
MacDermid played five games for Boston last season, getting into a fight in his NHL debut at the New York Rangers on March 4. The 22-year old winger had four goals, 12 assists and 121 penalty minutes in 69 AHL games with providence. MacDermid was drafted in the fourth round (112th overall) in the 2009 NHL entry draft.