Dickson played in 11 minor league games and went 7–3 with an 0.94 ERA and 111 strikeouts over 76+1⁄3 innings. After this performance he was called up to the major leagues and made his debut as the Cubs' starting pitcher on August 9, 1990. The second-youngest player in the league at the time of his promotion, Dickson's big-league career was nonetheless short-lived. He went 0–3 with a 7.24 ERA in his three starts, precipitating his return to the Triple–A Iowa Cubs. His last major league appearance was August 18.[5]
After Dickson went back to the minor leagues, he was chosen by the American Association managers as the best pitching prospect and possessor of the best breaking ball in the league. His record was 4-3 and had a 2.86 ERA in his 15 starts. Dickson led the league with 92 strikeouts in 91 innings before he was injured by a stress fracture in his right foot in June 1991. During the following offseason, he underwent arm surgery, and made only one start in 1992 as a result.[6]
Dickson split the 1993 campaign between the High–A Daytona Cubs, Double–A Orlando Cubs, and Iowa. In 14 starts for the three affiliates, he accumulated a 3–6 record and 4.08 ERA with 67 strikeouts across 70+2⁄3 innings pitched.[7] Dickson made 4 starts for Triple–A Iowa in 1994, recording a 4.91 ERA with 17 strikeouts over 14+2⁄3 innings of work.[8]
Dickson retired from baseball in 1995, having made only two scoreless appearances for the rookie–level Gulf Coast League Cubs during the season.[9]