[2] Compelled by the bonus rule to spend the first two years of his pro career on the Cubbies' big-league roster, Kaiser worked in only 11 games and 181⁄3 innings pitched in 1955, with no decisions and a high 5.40 earned run average.

Facing the defending world champion Brooklyn Dodgers at Wrigley Field, he allowed only two hits, four bases on balls and one run in a complete game, 8–1 triumph.

He began 1957 in the rotation and in his third start, on May 6, he defeated the New York Giants on six hits, 6–2, at the Polo Grounds,[6] for the sixth and last complete game of his career.

In his one late-season appearance, he turned in a mediocre start against the Cincinnati Redlegs, allowing four earned runs in four innings pitched—just enough to be tagged with Chicago's 4–3 defeat.

Kaiser would be included in off-season trades to the Braves in December 1957 and the Detroit Tigers in October 1959, but he never returned to the major leagues.