In his playing days, Slider stood 5 feet 8 inches (1.73 m) tall, weighed 160 pounds (73 kg), batted left-handed and threw right-handed.
In 1962, the Kansas City Athletics sold Slider's contract to the Red Sox, and he spent the remainder of his career in the Boston organization.
His next assignment, in 1967–1968 as skipper of the Class A Waterloo Hawks, saw the professional debut of eventual Hall of Fame catcher Carlton Fisk.
Slider spent nine seasons at the helm of the Red Sox' Winter Haven affiliate in the Class A Florida State League.
In 1983, his New Britain Red Sox won the Double-A Eastern League playoffs behind first-year pitcher Roger Clemens.