Signed by the Houston Colt.45s as an undrafted free agent directly out of Colton High School in June 1963, Dahl was sent to the Moultrie, Georgia Colt.22s of the Georgia–Florida League. Dahl dominated the league, with a 5-1 record and a 1.42 ERA—his only loss was a one-hitter, in his pro debut. After making one start for the San Antonio Bullets of the Double-A Texas League, he made his big-league debut on September 27, 1963 at Colt Stadium against the New York Mets. Dahl wasn't the only rookie in the lineup for Houston that night; in fact, the entire Colts starting nine were first-year players : ;Houston Colt.45s starting lineup, September 27, 1963
Dahl got New York out in the first inning, but allowed three runs in the second and four more in the third before being removed by manager Harry Craft. The Mets went on to win, 10-3. It was to be Dahl's only major league appearance. In 1964, Dahl developed back problems and did not pitch at all, appearing in eleven games as an outfielder for Statesville Colts in the Western Carolinas League. In 1965, Dahl was back on the mound, starting seven games with Carolina League's Durham Bulls, then moving over to the Salisbury Astros of the WCL, where he had a 5-0 record.
Death
At 11:24 p.m. on Sunday, June 20, 1965, Dahl's teammate Gary Allen Marshall was driving a GTO with two passengers: Dahl and 20-year-old Patricia Ann Troutman. Apparently traveling at a high speed, the car hit a patch of sand on Lincolnton Road in Salisbury, skidded out of control for about and slammed broadside into a tree. Troutman was killed instantly, and Dahl died of extensive internal injuries about three hours later in Salisbury's Rowan Memorial Hospital. Marshall survived the wreck but was blinded, also suffering a broken right arm and a broken right leg; he was later charged with manslaughter, but the charges were dismissed and he was allowed to return home to Hutchinson, Kansas. Earlier that day, Dahl had pitched the Salisbury Astros into first place; in celebration of his 7-3 victory over Gastonia, North Carolina, the players were the guests that evening at a steak dinner at the home of G. M. Hamilton, Salisbury's club president. Dahl and Marshall left after dinner and attended a movie with Troutman; they were returning her to her home when the crash occurred. As of July 2019, Dahl is the youngest player to die after appearing in the major leagues.
