Mark Eichhorn was a professional baseball player who played as a pitcher for several teams during his career. He was born on November 21, 1960, in San Jose, California, and attended Cabrillo College in Aptos, California.

Eichhorn was drafted by the Toronto Blue Jays in the second round of the 1979 Major League Baseball draft. He made his major league debut with the Blue Jays in 1982 and quickly established himself as a reliable relief pitcher. He was known for his unorthodox delivery, which involved a hesitation before releasing the ball.

Eichhorn played for the Blue Jays until 1990, during which time he was named an All-Star in 1986. He was traded to the Atlanta Braves in 1990 and played for them for one season before being traded to the California Angels in 1991.

Eichhorn had a successful season with the Angels in 1991, posting a 1.98 ERA and earning 11 saves. He was named the American League Comeback Player of the Year for his performance. He played for the Angels until 1993, when he was traded to the Baltimore Orioles.

Eichhorn played for the Orioles for two seasons before being released in 1995. He signed with the Boston Red Sox for the 1996 season but struggled with injuries and was released mid-season.

Overall, Eichhorn had a successful career as a relief pitcher, posting a career ERA of 3.67 and earning 166 saves. He was known for his durability and consistency, and his unorthodox delivery made him a difficult pitcher to face.

After his playing career, Eichhorn worked as a pitching coach for several minor league teams. He also wrote a book about his experiences as a major league pitcher, titled "The Unlucky Sperm Club: You Are Not a Victim of Your Genes, But a Product of Your Choices."