In 1970, after spending the season in the minor leagues with the Iowa Oaks of the American Association, Blue was called up in September, making two starts that provided a glimpse of what was to come. On September 11, he shut out the Kansas City Royals 3-0, giving up only one hit, to Pat Kelly in the eighth inning. Ten days later, he no-hit the Minnesota Twins, 6-0, at Oakland-Alameda County Coliseum, with the lone baserunner being Harmon Killebrew, who walked in the fourth inning.
Blue was a southpaw power pitcher. He possessed a breaking curveball that he threw on occasion and an above average change-up, but his signature pitch was a blistering fastball that dialed up to nearly 100 miles per hour. In The Neyer/James Guide to Pitchers, all-time hits leader Pete Rose stated that Blue ‘threw as hard as anyone’ he had ever faced, and baseball historian Bill James cited Blue as the hardest-throwing lefty, and the second hardest thrower of his era, to only Nolan Ryan.
Blue had a 24-8 record in 1971, winning both the Cy Young and MVP awards. He also led the American League in complete games (24), shutouts (8) and Earned run average (1.82), Only one other starting pitcher, Roger Clemens in 1986, has since won an MVP Award. That season, the Athletics won the American League West title for the franchise’s first postseason berth since the Philadelphia Athletics in the 1931 World Series. He was the youngest American League player in the 20th Century to win the MVP Award. He was the starting pitcher for the American League in the 1971 All-Star Game, and for the National League in the 1978 All-Star Game.
Blue won 20 games in 1973, 17 games in 1974, and 22 games in 1975, as an integral member of the Oakland Athletics five straight American League Western Division pennants from 1971-1975, and three consecutive World Championships in 1972, 1973, and 1974.