OXNARD, Calif. — Cornerback Morris Claiborne has had both bad luck and bad health since the Cowboys made him the sixth overall pick in 2012. He has had hamstring, shoulder and knee injuries as well as a concussion, missing seven regular-season games in his first two seasons.Claiborne has yet to make it through a training camp unscathed.He had just returned to practice this week when Claiborne landed hard on his right shoulder Wednesday."I just landed on it," said Claiborne, who had been out with tendinitis in his knee since July 30. "It was kind of an awkward land."Claiborne and Raiders receiver Andre Holmes got tangled on a ball thrown by Matt Schaub. To add insult to the injury, Claiborne drew a flag as he hit the ground hard. "I felt like he took me down, but I’m going to leave that for somebody else," he said. "I just landed on it wrong."Claiborne had offseason surgery on his left shoulder after injuring it in the 2013 season opener. He said he does not fear missing any more time, even though he sat out the rest of Wednesday’s team drills."It’s not like it came out or anything," Claiborne said. "It was just one of those freaky lands. It’s good."