You don't have enough time to "react" to anything faster than a spinner.
You are able to get everything lined up in time (your feet, head, bat) because of the thousands of balls you have faced in training and in games. You have a mental database of all these little cues, so you are able to determine the trajectory of the ball before it is even bowled.
The more practice you do, the more balls you face, the bigger your database becomes and the better you will be able to bat.
When batsman are faced with an unfamilar action (i.e. a slinger) they struggle to pick the ball up and are constantly 'late on the ball' because their database of that type of bowling is much smaller. Which is why I believe people have such a romantic notion that Thomson is bowling 180kph etc
A noteable example: (I emplore you to read this, its an exerpt from a book called "The Sports Gene" - a book I would wholehartedly recommend to anyone interested in the science behind sports, there is many anecdotes from a wide variety of sports)
Female softball pitcher throws to the worlds best baseball players, they can't even get bat on ball.
"All right," Pujols said softly, indicating he was ready.
Finch rocked back and then forward, whipping her arm in a giant circle. She fired the first pitch just high. Pujols lurched backward, startled by what he saw. Finch giggled.
She unleashed another fastball, this time high and inside. Pujols spun defensively, turning his head away. Behind him, his professional peers guffawed.
Pujols stepped out of the batter's box, composed himself and stepped back in. He twisted his feet into the dirt and stared back at Finch.
The next pitch came right down the middle. Pujols uncoiled a violent swing. The ball sailed past his bat, and the spectators hooted.
The next pitch was way outside, and Pujols let it go. The one after that was another strike, and Pujols whiffed again. With one strike remaining, Pujols moved to the back of the batter's box and dug in, crouching low in his stance.
Finch rocked and fired. Pujols missed badly. He turned and walked away, toward his tittering teammates. Then he stopped, bewildered. He turned back to Finch, doffed his cap and continued on his way.
"I never want to experience that again," he later said.
*****
The fielders behind Finch had good reason to sit down when she entered the 23rd Pepsi All-Star game: They knew there would be no hits. Just as she had during practice, Finch struck out both hitters she faced. Piazza, the Mets' catcher, went down on three straight pitches. Padres outfielder Brian Giles missed so badly on the third strike that his momentum spun him through a pirouette.
Then Finch returned to her role as a ceremonial coach. But she was not nearly finished befuddling major leaguers.
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."
*****
For four decades, scientists have been constructing a picture of how elite athletes intercept speeding objects. The intuitive explanation is that the Albert Pujolses and Roger Federers of the world simply have the genetic gift of quicker reflexes, which give them more time to react to the ball. Except that isn't true.
When people are tested for their simple reaction time -- how fast they can press a button in response to a light -- most of them, whether they are teachers, lawyers or pro athletes, take around 200 milliseconds, or one fifth of a second. That is about the minimum time it takes for the retina at the back of the human eye to receive information, for that information to be conveyed across synapses -- the gaps between neurons, each of which takes a few milliseconds to cross -- to the primary visual cortex in the back of the brain, and for the brain to send a message to the spinal cord that puts the muscles in motion. All this happens in the blink of an eye. (It takes 150 milliseconds just to execute a blink when a light is shone in your face.) But as quick as 200 milliseconds is, in the realm of 100-mph baseball pitches and 140-mph tennis serves, it is far too slow.