Day was the most outstanding pitcher in the Negro National League during the late 1930s and early 1940s. A heady pitcher, he was the Newark Eagles‘ ace. He had a sneaky fastball, which he delivered with a no-windup, sidearm motion and complemented with a good curve and change-of-pace to set impressive strikeout records.
Day was also a good hitter and baserunner. When not pitching, he often played second base or the outfield, or pinch-hit.
Day’s best season was 1937, when, backed by the Eagles’ “million-dollar infield,” he was 13-0 in league play and batted .320. In 1940 he established the Puerto Rican record of 19 strikeouts while locked in an 18-inning marathon with spitballer Bill Byrd; the game was called with the score tied 1-1. He also played two winters in Cuba and one in Venezuela (going 12-1), and three summers in Mexico.
Day appeared in a record seven East-West all-star games from 1935 through 1946, winning his only decision and setting an all-star record by striking out a total of 14 batters. In the 1942 game, he struck out five of the seven he faced without giving up a hit. That year he set a Negro League record when he struck out 18 Baltimore batters in one game, including Roy Campanella three times. For post-season play, he was recruited by the Homestead Grays to oppose Satchel Paige in the Negro World Series; he struck out 12 batters in a 4-1 victory.
Day served in the army during WWII, was discharged in February 1946, and threw an Opening Day no-hitter against the Philadelphia Stars. He recorded a 9-4 record that year, led the league in strikeouts, and started two games in the Negro World Series, in which the Eagles defeated the Kansas City Monarchs.
After pitching for the 1949 champion Baltimore Elites, Day left to play in Canada in 1950. Then, well past his prime, he entered organized baseball, pitching for Toronto (International League) in 1951 and Scranton (Eastern League) in 1952 before returning to Canada, where he finished his career in 1955.