Keegan was listed as 6feet 2inches (1.88m) tall and 207 pounds (94kg). He was 32 years old when he made the 1953 White Sox' varsity roster, and in his sophomore season, 1954, he was selected to the American LeagueAll-Star team. In the game, played July 13 at Cleveland Stadium, Keegan started the eighth inning in relief with the Junior Circuit ahead, 8–7. Keegan retired his first batter, Randy Jackson, then surrendered a single to Willie Mays. He struck outRoy Campanella, but then gave up a pinch hithome run to Gus Bell to put the Nationals ahead, 9–8. Red Schoendienst then reached on an error and Alvin Dark singled before Keegan was lifted. His replacement, left-hander Dean Stone, never threw an official pitch, but picked off Schoendienst as he attempted to steal home for the third out. Stone then became the winning pitcher when the American League rallied for three runs in the bottom of the eighth to claim an 11–9 triumph.[1]
Despite his rough treatment in the midsummer classic, Keegan's 1954 season was his finest. He posted a 16–9 won–lost record with a 3.09 ERA in 2092⁄3innings pitched. His 14 complete games that year was ninth in the league and a personal best.
1957 was Keegan's last full year in the majors. In the early weeks of 1958, he was sent to the minor leagues and joined his hometown Rochester Red Wings in 1959, winning 18 games. He pitched one more year with Rochester before retiring after 15 professional baseball seasons. In the majors, he went 40–36 lifetime, with 3.66 earned run average. In 135 career games, with 87 starts, he threw 29 complete games and six shutouts; he was credited with five saves as a reliever. In 6442⁄3MLB innings pitched he allowed 668 hits and 233 bases on balls, with 198 strikeouts.