As Orioles position players continue to trickle in ahead of the club's first full workout Friday, one player has been noticeably absent from the team's clubhouse. And given the concussion symptoms that have limited second baseman Brian Roberts to 98 games the past two seasons, he is one of the biggest question marks in camp. On Tuesday, the switch-hitting Roberts was spotted hitting balls from a tee for about 15 minutes in the team's indoor batting cages at the Ed Smith Stadium complex. Upon exiting, Roberts said he would speak to the media Friday about his progress but said that other than hitting off a tee, he has been playing catch and doing light weightlifting. "All a part of the progression," he said.