Josh Johnson's sore arm might be the result of nerve damage that could force the Marlins' right-hander to miss the first month of the season or more. Three MRI exams Friday showed no ligament or rotator cuff problems, and a bone scan was normal, agent Matt Sosnick said. "They think it's probably a nerve thing," Sosnick said. "The worst-case scenario is probably that he would be out eight to 12 weeks, but they have to figure out what this thing is." More tests are planned. Regardless of the results, Johnson is likely to miss the start of the season.