In, Goodwin pitched for the Martinsburg Blue Sox of the Class D Blue Ridge League, starting and completing 31 games with a record of 19–12, with 10 shutouts. His major league debut came in September of that year, when he appeared 3 times in relief for Washington, pitching innings and giving up two earned runs. Goodwin started the season with the Milwaukee Brewers of the American Association, and compiled a record of 8–9 with a 1.91 ERA, before being acquired by the St. Louis Cardinals in July. With the Cardinals his record for the season was 6–4 with a 2.21 ERA.
In December 1917, Goodwin joined the United States Army. Being unmarried and with no dependents, he told the Cardinals he was sure to be drafted, so he enlisted in order to join the aviation corps. He was stationed in Texas, where he successfully completed his training, and became an aviation instructor. He was preparing to deploy to France when the war ended in November 1918.
Baseball career after World War I
After the war, Goodwin rejoined the St. Louis Cardinals. In his record was 11–9 with a 2.51 ERA, and in his record was 3–8 with a 4.95 ERA. For and he split time between the Cardinals and their farm club, the Houston Buffaloes of the Texas League, and then spent all of the 1923 and 1924 seasons with Houston. In May 1924, Goodwin became player-manager of the Houston club, a role he continued through the next season. Late in the season he was sold to the Cincinnati Reds; he appeared in four games for the Reds, compiling a 0–2 record with a 4.79 ERA. His final major league appearance came on the final day of the season, when he pitched a complete game in the first half of a doubleheader, but lost 4–2.
Death
Two weeks after his final appearance with the Reds, Goodwin crash landed his airplane at Ellington Field on October 18, 1925. The accident occurred during a training exercise when he was performing reserve duty with the United States Army Air Service. Goodwin experienced a tailspin about 200 feet in the air. He was hospitalized with serious injuries including two broken legs. His piloting skills were credited with saving him from immediate death. Goodwin died on October 21, 1925, from the injuries he sustained three days earlier.
Legacy
As noted by The Sporting News, "Marvin was a gentleman and an athlete of whom baseball can be proud... Lieutenant Goodwin sacrificed his life in behalf of his country. No person can do more." Goodwin is buried in Maplewood Cemetery in his hometown of Gordonsville.