First signed by the Rangers, Nelson jumped from the Florida State League (20-3 in 1980) to the Yankees in 1981; at 20, he was the youngest player in the majors. In 1982 he was traded to Seattle, but failed to impress the Mariners and was drafted off their Triple-A roster by the White Sox, who used him as a setup man and spot starter.
Chicago manager Tony LaRussa liked Nelson’s work habits. After LaRussa took over at Oakland in 1986, he had the A’s acquire Nelson, who won Games Two and Three of the 1988 LCS with scoreless relief. He went on to pitch well in Oakland’s two World Series defeats in 1988 and ‘90, giving up only one run in 11.1 innings, but surrendered six runs in his only inning of work during Oakland’s 1989 World Series victory.