The Detroit Tigers placed shortstop Carlos Guillen on the 15-day disabled list Wednesday with a sore right knee. The move is retroactive to Thursday, August 11. This is the second time Guillen has been on the disabled list this season. The switch-hitter was shelved on June 14 because of a pulled hamstring. On the season, Guillen is batting .318 with five homers and 23 runs batted in. The Tigers recalled first baseman Carlos Pena from Triple-A Toledo to replace Guillen on the active roster.