ACC Player of the Year Cooper Flagg was ruled out for Duke’s conference tournament semifinal matchup with North Carolina on Friday night in Charlotte.Flagg sprained his left ankle in the first half of Duke’s quarterfinal victory over Georgia Tech on Thursday and did not return to the game. Head coach Jon Scheyer said Flagg was a “long shot” to play Friday and pointed to the big picture — next week’s NCAA Tournament — as the guide in making any decision on Flagg’s status.X-rays taken at the stadium Thursday were negative, Scheyer confirmed, but significant swelling was an immediate concern.Flagg averaged 18.9 points (third in the ACC), 7.5 rebounds (ninth) and 4.1 assists (eighth) as the spotlight fixture for Duke’s top-ranked freshman class.