Gary Sheffield says he isn't as seriously injured as he first feared when he experienced numbness in his right arm. A day after the Detroit Tigers designated hitter had X-rays and an MRI exam, he said the injury stemmed from when he fell on his right elbow in a collision with second baseman Placido Polanco on July 21. Sheffield's collar bone, which he said was dislocated early in his career, was pushed out of place and caused numbness and soreness in his right shoulder. "I have to do rehab, just like pitchers," Sheffield said. He won't go on the disabled list, began taking medicine Thursday and started therapy and rehab on Friday.