The union says Weiner died Thursday at his home in Mansfield Township, N.J.
Weiner was a plain-speaking labor lawyer known for his casual dress and easygoing manner. He took over as head of the powerful union four years ago and helped smooth its often-contentious relationship with MLB management.
A succession plan was put in place last summer that will lead to former big league All-Star Tony Clark taking over Weiner's role as executive director.
