Baker strained his groin on May 22 in Boston while running the basepaths.
Baker has been used in a do-it-all role for the Cubs this season, playing five different positions. He's hitting .368 with one home run and seven doubles while leading the league with a .512 average against lefties.
He had been labeled as day to day, but has only had two pinch-hit at-bats since incurring the injury. Manager Mike Quade has been hesitant to play Baker in the field, fearing that he would do further damage to his groin.
Infielder D.J. LeMahieu was called up from Double-A to fill Baker's roster spot. LeMahieu, who attended LSU, was the Cubs' second-round draft pick in 2009. The 22-year-old is hitting .358 with 15 doubles, two triples and two home runs for the Tennessee Smokies.
Sahadev Sharma and Bruce Levine cover the Chicago Cubs for ESPNChicago.com.