it is not recognized because people aren't paying attention to it, like baseball, and get another concussion on top of it, that's not just potentially a small problem, that's a potentially lethal problem. >> reporter: increasingly, concussions are sidelining some of baseball's brightest stars. this season alone, 28 major leaguers suffered concussions. twins catcher joe mauer, tigers catcher alex avila, and others players like nick hunt lee wonder if they'll be safe in retireme retirement. >> you play through concussion stuff and play through the long term effects, i just had a daughter, it puts it in perspective a little more. >> reporter: major league baseball is trying to better protect players. implemented a concussion disabled list, separate from the 15 day disabled list to encourage more players to admit they have a problem. >> now that we started to