Niekro, like his brother, specialized in throwing the knuckleball, and his 221 career victories make him one of the most successful knuckleball pitchers of all time. The Niekro brothers combined for 539 total wins, making them the winningest brother combination in baseball history.
Joe Niekro was much more traveled than his brother, pitching for the Chicago Cubs, San Diego Padres and Detroit Tigers with only occasional success before joining Phil with the Atlanta Braves in 1973. While pitching for Atlanta, Niekro perfected his knuckleball, and two years later joined the Houston Astros, where he would become the winningest pitcher in Astros history. He was an All-Star in 1979, a year in which he led the National League in wins with 21, threw a league-leading five shutouts, and finished second in voting for the National League Cy Young Award.
The Niekro brothers were briefly reunited again in 1985 when Joe was acquired by the New York Yankees. In June 1987, the Yankees traded Niekro to the Minnesota Twins. A month later, on August 3, 1987, Niekro was ejected for having a nail file on the mound. Niekro claimed he had been filing his nails in the dugout and stuck the file in his back pocket when the inning started and had not been doctoring baseballs. The league president didn't believe him and suspended Niekro for 10 days.
When Niekro appeared in the 1987 World Series, he set a record for the longest period of time elapsed between a player's major league debut and his first appearance in the World Series.
On May 4, 1988, after compiling a 10.03 earned run average in his first five games, the Twins released Niekro, ending his 22-year career.