Freshman Cooper Flagg put on a show in a return to New England, pouring in 28 points as No. 3 Duke blew out Boston College in the second half of an 88-63 victory Saturday night at Chestnut Hill, Mass.Tyrese Proctor added a season-high 20 points and Isaiah Evans racked up 16 points off the bench as the Blue Devils (16-2, 8-0 Atlantic Coast Conference) rang up their 12th consecutive victory.Duke used a big burst early in the second half, including a 7-0 run to stretch a six-point lead to 13. The margin grew as large as 27 points.Chad Venning scored 19 points on 7-for-11 shooting from the field for Boston College (9-9, 1-6), which has lost four games in a row. Donald Hand Jr. had 12 points.Flagg, a heralded forward who’s from Maine, made nine of 14 shots from the field and went 9-for-11 from the line. He also was tagged with a late-game technical foul to go with five rebounds and four assists.Duke withstood some moderate foul trouble, with center Khaman Maluach saddled with four fouls by early in the second half.The Blue Devils shot 52.6 percent from the field, making it seven games in a row with a mark of at least 50 percent. Duke posted another double-digit victory (their 14th) despite Kon Knueppel going scoreless on 0-for-5 shooting from the field.