Rangers left-hander Martin Perez has struggled at the Double-A level this season. The 19-year-old has started 21 games for the Frisco RoughRiders of the Texas League. Perez has gone 4-7 with a 5.87 ERA in 87 1/3 innings. The lefty has 88 strikeouts and 44 walks, good for a perfect 2-to-1 K/BB ratio. He has struggled more so over his last ten appearances, going 2-4 with a 6.48 ERA in 41 2/3 innings. Perez signed with Texas as a non-drafted free agent in 2007. Baseball America listed him as the 17th-best prospect prior to the 2010 season.