On Tuesday, Roberts saw concussion specialist Dr. Michael Collins and was told he needed more rest. Roberts, who hasn't played since May 16, will be re-evaluated in two weeks.
Although Roberts is making progress, he's still experiencing some concussion symptoms, including headaches after working out. He is permitted to do conditioning work, but nothing else.
The concussion, suffered after sliding head-first into first base to beat out an infield single, was his second in the last year. Roberts has played in just 39 of the team's 70 games this season.