The Athletics announced the death Saturday night without providing details.

“Matt was a great baseball man and a proud Oakland A,” Billy Beane, the team’s executive vice president of baseball operations, said in a statement.

“He had an incredible passion for the game and we were lucky to have him and his wealth of knowledge alongside us for the years he worked as a special assistant. He left an unforgettable impression on everyone he touched in baseball. Our sincere condolences are with the entire Keough family tonight.”

Keough was an American League All-Star as a rookie in 1978 and was selected AL Comeback Player of the Year in 1980. He was 58-84 with a 4.17 ERA with Oakland (1977-83), the New York Yankees (1983), St. Louis (1985), Chicago Cubs (1986) and Houston (1986), then went 45-44 with a 3/73 ERA in Japan with Hanshin (1987-90).

Keough’s father, Marty and uncle, Joe, were major league outfielders.