Major League Baseball announced today that it has approved a roster substitution for the Toronto Blue Jays due to a concussion sustained by left-handed pitcher Francisco Liriano. Liriano will be replaced on the Division Series roster by right-handed pitcher Danny Barnes. 
MLB Postseason rules provide that a Club may request permission from the Commissioner's Office to replace a player who is unable to play because of an injury. The Commissioner's Office may approve or disapprove the request based on the specific facts and circumstances. In accordance with Major League Rule 40(a)(4)(C), Liriano will be eligible to return during any Postseason series, provided that he has been ineligible to play for a minimum of seven days (beginning today), and Major League Baseball's Medical Director has approved a reinstatement.
Major League Rule 40(a)(4)(C)
The injured player being replaced shall be ineligible to play for the remainder of such series, as well as the next subsequent post-season series that year. Notwithstanding the foregoing, a replaced player, who has suffered an acute concussion during a post-season series, may be eligible to play in the next subsequent post-season series that year, provided that the player has been ineligible to play for a minimum of seven days, and Major League Baseball's Medical Director has reviewed a Return to Play form and supporting information and approved the reinstatement.