In 2004 and '05, Finch hosted a regular segment on Fox's This Week in Baseball in which she traveled to major league training camps and transformed the world's best baseball hitters into clumsy hacks. "Girls hit this stuff?" asked an incredulous Mike Cameron, the Mariners' outfielder, after he missed a pitch by half a foot.
When seven-time National League MVP Barry Bonds saw Finch at the Major League All-Star Game, he walked through a throng of reporters to talk trash to her. "So, Barry, when do I get to face the best?" Finch asked.
"Whenever you want to," Bonds replied confidently. "You faced all them little chumps.... You gotta face the best.
"You can't be pretty and good and not face another handsome guy who's good," Bonds added, spreading his peacock feathers. He then told Finch to bring a protective net because, he said, "you're going to need it with me.... I'll hit you."
"There's only been one guy who touched it," Finch replied.
"Touch it?" Bonds said, laughing. "If it comes across that plate, believe me, I'ma touch it. I'ma touch it hard."
"I'll have my people call your people, and we'll set it up," Finch said.
"Oh, it's on!" Bonds said. "You can call me direct, girl. I take my challenges direct.... We'll televise it too, on national television. I want the world to see."
So Finch traveled to Arizona to face Bonds in spring training, and after he watched several of her pitches fly by, the raillery stopped. He insisted that the cameras not film him batting against her. Finch shot pitch after pitch past Bonds as his Giants teammates pronounced them strikes. "That's a ball!" Bonds pleaded, to which one of his teammates replied, "Barry, you've got 12 umpires back here."
Bonds watched dozens of strikes go by without so much as swinging. Not until Finch began to tell Bonds what pitches were coming did he tap a meek foul ball a few feet. He taunted her, "Go on, throw the cheese!" She did, and blew it right past him.
Finch visited Alex Rodriguez, who was then starring for the Rangers, at another spring-training park, in 2003, and Rodriguez watched over her shoulder as she threw warmup pitches to a Texas bullpen catcher. The catcher missed three of the first five throws. Before Rodriguez stepped into the batter's box, he made it clear he wouldn't dare swing at any of Finch's pitches. He leaned forward and told her, "No one's going to make a fool out of me."
One of the first mysteries he tackles is this one: why did MLB's best hitters, who have to hit baseballs that travel to home plate in about 400 milliseconds from just under 60 feet 6 inches away, struggle to even make contact with a much larger softball traveling to home plate in the same amount of time (thrown slower at 68mph, but from a shorter distance).
Epstein notes that the average time for a major league hitter to initiate muscular action is about 200 milliseconds, meaning baseball players must decide to swing at a baseball before it's even halfway to home plate. To make that decision, baseball players try to anticipate the pitch being thrown by looking at the pitcher's delivery motion.
This explains why certain pitches and pitchers are so effective. Take Mariano Rivera, for example. For much of his career, he threw just one pitch, the cutter. How can a pitcher survive throwing one pitch such a high percentage of the time? In fact, this season he's thrown the cutter 89% of the time.
The key is late movement. The batter has to decide to swing at the ball and where to swing before the pitch is halfway to home plate, but the pitch tends to move laterally and downwards, away from the arm side, very late in its path to the plate. By then it's too late for a hitter to adjust his swing path. The same principle applies to the slider which may be the single pitch most responsible for the rise in strikeouts in the modern era. It comes in looking like a fastball, and the best sliders move both sideways and away from the arm side very late, too late for a hitter to do anything about his swing path.
Why is Yu Darvish such a tough pitcher to hit? Part of it is his filthy and broad repertoire of pitches, but another is the fact that he manages to deliver every pitch to multiple locations with the same exact motion, leaving the hitter with fewer cues to try to guess which pitch is coming. This animated GIF that circulated earlier this year illustrates this deception beautifully.
Even skills that appear to be purely instinctive, such as jumping to rebound a basketball after a missed shot, are grounded in learned perceptual expertise and a database of knowledge about how subtle shifts in a shooter's body alter the trajectory of the ball. Without that database, which can be built only through rigorous practice, every athlete is a chess master facing a random board, or Albert Pujols facing Jennie Finch: He is stripped of the information that allows him to predict the future.
Since Pujols had no mental database of Finch's body movements, her pitch tendencies or even the spin of a softball, he could not predict what was coming, and he was left reacting at the last moment. And Pujols's simple reaction speed is downright quotidian. When scientists at Washington University in St. Louis tested him, perhaps the greatest hitter of his era was in the 66th percentile for simple reaction time compared with a random sample of college students.
It's true, some hitters will guess that a certain pitch is coming, and if they guess incorrectly they can look silly, letting a fastball right down the middle go by without lifting the bat off their shoulders. Being labeled a "guess hitter" was a stigma.
From Epstein's summary of how hitters operate at a neurological level, however, it turns out almost every hitter is guessing in some ways, from the moment the pitcher starts his motion to just after the baseball is released.