Tuesday, the Major League Baseball Players Association announced that Executive Director Michael Weiner is undergoing treatment for a brain tumor.
According to the Players Association, Weiner's treatment began Monday, and he will continue to work from the Association's New York office.
Weiner, 51, took over as Executive Director in December 2009, having previous served as general counsel.
Weiner is just the third Executive Director since the 1960s, following Marvin Miller (1966-1982) and Don Fehr (1983-2009). Weiner has generally taken a significantly less aggressive posture, publicly at least, than his predecessors. He presided over the negotiations for the latest Collective Bargaining Agreement between the players and owners, which began this year and runs through 2016, ensuring 21 straight seasons without a work stoppage.