Chris Getz of the Kansas City Royals remains out of the line-up after a concussion he sustained on Sunday. MLB.com (video at the link with story) ran a recent story about his situation and how Ned Yost, the Royals manager, have learned from previous injuries.
In 2006 while Yost was with the Milwaukee Brewers, third-baseman Corey Koskie dove for a ball and while never hitting the ground became concussed. Koskie has never returned to the sport.
Koskie along with Mike Matheny, MLB catcher, have had their playing days cut short by concussions. Of most note this season is all-star and MVP, Justin Morneau, who has been out of action since early July. Morneau took and inadvertent knee to the head while sliding into second base. He progressed to the point of traveling with the team with intentions of playing and quickly regressed. It is unknown if Morneau will return this season.