Brian Knight has retired as a major league umpire because of injuries and was replaced on the major league staff Friday by Charlie Ramos. Knight, 50, made his major league debut on May 7, 2011, as the third base umpire for Texas’ home game against the Chicago White Sox and was promoted to the major league staff in 2011. Knight was the plate umpire for Jon Lester’s no-hitter against Kansas City at Boston’s Fenway Park on May 19, 2008.