Slade scored 5275 runs at 18.06 and took 502 wickets at 23.47 with his slow left hand bowling in a career with Worcestershire that lasted from 1958 until 1971.
Slade came to prominence in his first season by taking 52 cheap wickets. 97 wickets (19.83) saw him attracting the attention of the cricket press. A useful batsman, Slade appeared to have a chance of a significant career. However the advent of Norman Gifford in 1960 began to restrict Slade's opportunities. He played only twice in 1961 and when he did make the First Eleven, he found himself frequently used as the sixth bowler. The registration of Basil D'Oliveira further restricted Slade's prospects. Apart from 71 wickets in 1963, he became a bit part player, though he scored 634 runs in 1969, scoring 125 against Leicestershire at Grace Road, one of two centuries.