Dallas Mavericks guard Kyrie Irving has been ruled out for Friday's game against the host Atlanta Hawks due to a sprained right thumb. Irving sustained the injury in Dallas' 119-110 setback to the Boston Celtics on Monday. The eight-time All-Star did not play in the Mavericks' 132-109 home loss to the Phoenix Suns on Wednesday. Atlanta star guard Trae Young, who leads the team in scoring at 26.9 points and assists at 10.8, was placed in concussion protocol after the game against the Cleveland Cavaliers on Saturday and missed the past two contests. Young also missed a Jan. 19 game with an illness. He is listed as questionable against the Mavericks. Irving, 31, averages 25.2 points, 5.3 assists and 5.1 rebounds in 27 games (all starts) this season for the Mavericks. …