Rick Shapiro, a longtime attorney for the Major League Baseball Players Association, has been let go by the union after being increasingly marginalized in recent months, according to sources.

Shapiro's departure comes at a time when the union is gearing up for what will be an important and perhaps contentious round of collective bargaining with Major League Baseball. The current agreement, negotiated in December of 2016, is set to expire after the 2021 season, and the two sides have agreed to begin discussions this summer -- although it's currently unclear whether there is hope of immediate progress.

Tony Clark, the head of the players association, has been outspoken in his dissatisfaction with recent trends in the game, particularly in the way that veteran players have fared in free agency.

Last summer, Clark brought on Bruce Meyer, who had served as counsel for the NHL Players Association.

Shapiro had been heavily involved with past CBA talks and the union's arbitration arguments.