The message from Joe Torre shown on the video board at AT&T Park was clear and direct: ''When in doubt, sit it out.'' From the World Series to the NFL, from hockey to youth sports, concussions are a major topic at all levels of athletics. They shaped part of the postseason for the San Francisco Giants - first baseman Brandon Belt returned from one, backup catcher Hector Sanchez didn't. Torre, the former catcher and Hall of Fame manager who's now a Major League Baseball executive, taped public-service announcements that appeared at ballparks in October, reiterating that head injuries need to be checked. The wild-card Oakland Athletics lost catcher John Jaso and outfielder Craig Gentry before the playoffs because of concussion effects.