Born in Brooklyn, New York, Koufax was a natural athlete as a child, excelling particularly on the basketball court, which helped win him an athletic scholarship to the University of Cincinnati. While there, he pitched occasionally for the baseball team and caught the eye of scouts from his hometown Brooklyn Dodgers with whom he signed a contract in 1955. Although he was a long way from being ready for the major leagues, the rules at the time stipulated that -- because he had received a then-substantial signing bonus -- he had to spend two years in the majors before being sent to the minor leagues. Ironically, the Dodgers cut their future manager, Tommy Lasorda, to make room for Koufax.
Blessed with a blazing fastball but little command of it, Koufax played for Brooklyn for three seasons (1955-57) with limited success. He was still a fan favorite with the Jewish community, however. After the team moved to Los Angeles in 1958, Koufax continued in the same role, pitching long relief with an occasional start.
He had been making slow but steady progress as a pitcher until 1961, when a teammate, catcher Norm Sherry, advised him he was overthrowing and could be a more effective pitcher if he would just "ease off a bit." Koufax took the advice to heart and had a fine season, winning 18 games that season.
The next year, when the Dodgers moved into Dodger Stadium, a ballpark which strongly favored a power pitcher, Koufax exploded all at once. He missed a third of the season with injuries -- predominantly a circulatory problem in his left index finger and a subsequent infection. By the time he had recovered, the Dodgers were out of pennant contention and it was decided to rest Koufax so as to enable a full recovery. He did, however, lead the National League in ERA with a mark of 2.54 and pitched Dodger Stadium's first no-hitter against the New York Mets on June 30.
In 1963, Koufax won the pitchers' Triple Crown, leading the league in wins (25), ERA (1.88) and strikeouts (306). He finished the season as the winner of the Cy Young Award (the first unanimous choice), league MVP award and his second no-hitter, this one against a powerful San Francisco Giants lineup including Willie Mays and Orlando Cepeda. After throwing two complete games (giving up a total of 3 runs) in the Dodgers' sweep of the New York Yankees he was also chosen as MVP of the World Series. Legendary Yankees catcher Yogi Berra later said "I can see how he won 25 games. What I don't understand is how he lost 5."
Whilst he repeated as ERA champ in 1964 while going 19-5, his shoulder problems increasingly troubled him causing him to miss 12 starts. Injuries did not preclude him tossing a third no-hitter, facing the minimum 27 Philadelphia Phillies, striking out 12 and allowing only one base runner -- a fourth inning walk.
On September 9, 1965, he eliminated even that imperfection, throwing a perfect game against the Chicago Cubs, becoming the first man to throw no-hitters in four consecutive seasons. The same year, Koufax and the Dodgers won the World Series again, while he captured his second Cy Young (again unanimously). In the Series Koufax was widely praised for refusing to pitch Game One due to his observance of Yom Kippur, but was hit hard in Game Two as the Minnesota Twins took an early 2-0 lead. The Dodgers fought back, with Claude Osteen, Don Drysdale and Koufax picking up vital wins to force a seventh game. Starting on only two days rest, Koufax took the ball and, despite not having good command of his curveball and pitching through tiredness and arthritic pain, threw a three hit shutout to clinch the Series. The performance was enough to win him his second World Series MVP awards. He won his second Triple Crown with a 26-8 record, 2.04 ERA and 382 strikeouts, a major league record that stood until Nolan Ryan broke it by one in 1974.
Koufax won his third Cy Young Award and third Triple Crown in 1966, going 27-9 with a 1.73 ERA and 317 strikeouts. But after the Dodgers lost the World Series, he announced his retirement, stating that the arthritis in his left arm was making it too painful to continue and that the club doctor had advised him that to pitch on would run the risk of permanent arm injury. After a five year career as a colour commentator for NBC, retired from public life and into the privacy that had marked much of his playing career.
His career record was 165-87, with a 2.76 ERA.
Whereas most left handed pitchers throw, to some degree or other, with a three-quarter or sidearm motion, Koufax threw with a pronounced over-the-top arm action. This may have increased his velocity, but reduced the lateral movement on his pitches, especially movement away from left-handed hitters. Most of the velocity, however, came from his deceptively strong legs and back combined with a high kicking wind-up and long forward stretch toward the plate. Throughout his career he on relied two pitches: his four-seam fastball had a "rising" motion due to underspin and appeared to move very late; the overhand curveball, spun with the middle finger, dropped vertically ("12-to-6") due to his arm action. He also occasionally threw a changeup and a forkball.
At the beginning of his career he worked with coaches to eliminate his tendency to "tip" pitches (i.e. give away which pitch was coming due to variations in his wind up). By the end, and especially as his arm problems continued, this variation (usually in the position he held his hands at the top of the wind-up) was even more pronounced and good hitters were rarely unsure what pitch was coming. It did not usually help.