Rangers put Martinez on DL, call up Irwin to start
Irwin was set to start Tuesday night's game against Houston in his Rangers debut. His only other major league appearance was a start for Pittsburgh on April 13, 2013.
Martinez has discomfort in his left side, and the move was retroactive to July 2.
Martinez is 1-6 with a 5.10 ERA over 16 games (11 starts) for the Rangers.
Irwin was 4-1 with a 2.41 ERA in seven games (six starts) for Round Rock. Texas got him on a waiver claim from Pittsburgh on May 28.