Her biggest skill, however, was that she hurled pitches with startling accuracy, and had an uncanny knack for pinpointing a player's weakness. When Chattanooga Lookouts owner Joe Engel saw her playing in Georgia, he decided he had to have her on his minor league team.
Whether or not Engel knew her full potential is debatable. As the self-professed "Barnum of Baseball", Engel was known for press-friendly stunts, like when he traded his shortstop for a 25-pound turkey. As soon as he signed Mitchell, he began promoting the Lookouts as the only team in baseball with a female pitcher.
Amazingly, Mitchell's first game as a pro was in an exhibition game against the Yankees. And her first pitch was against Babe Ruth! Here's how the Baseball Hall of Fame describes it:
In the first inning, after starter Clyde Barfoot surrendered hits to the Yankees' first two batters, Mitchell was called upon to face the heart of "Murderers' Row," Babe Ruth and Lou Gehrig... [Her] uncanny knack came in handy when Mitchell faced Ruth, who watched her first sinker dart low for ball one. Mitchell followed with a sinker on the outside corner, which the Babe swung through and missed. Grinning, the "Sultan of Swat" swung at the next offering and missed for strike two. The next pitch was another sinker on the corner of the plate, which Ruth watched sail by for called strike three. At that point, the Babe "kicked the dirt" and "gave his bat a wild heave" as he stormed unhappily to the dugout... Next up was Gehrig, who promptly missed three straight dipping sinkers, swinging early each time. On seven pitches, Mitchell had struck out Ruth and Gehrig, two of the game's greatest sluggers. The Chattanooga crowd responded with a rousing standing ovation. Mitchell faced the next Yankees' batter, second baseman Tony Lazzeri, who tried to bunt the first pitch but failed. Lazzeri eventually walked and Mitchell was removed from the game. Engel had maximized her gate appeal by using her to face the heart of baseball's greatest lineup. The 17-year old had squared off against three future Hall of Famers, striking out two of them. The next day, one newspaper would speculate that "maybe her curves were too much for them."
Sadly, Mitchell's game against the Yankees also proved to be her last. Just days after her legendary performance, commissioner Kenesaw Mountain Landis voided her contract. Citing that the sport was "too strenuous for women," Landis essentially wrecked Mitchell's professional career. While Jackie went on to tour with other prominent female athletes (like Babe Didrikson) and play on women's teams for short spells, she bowed out of sports at just 23.