Luis Perdomo's worst start as a big-leaguer has resulted in the right-hander's demotion to Triple-A El Paso, the San Diego Padres announced Thursday. Perdomo, 24, allowed nine runs (seven earned) in three innings in a 13-4 loss to the Los Angeles Dodgers on Wednesday. Perdomo was 8-11 with a 4.67 ERA a year ago in his second season in the majors.