The Physics of Baseball
Yu Darvish is a 26-year old pitcher from Japan. His throwing motion for different kinds of pitches is so similar, it makes it very difficult for batters to detect what's coming. (This animated GIF shows 5 pitches superimposed in one image: watch how his arm follows a similar path, but the balls go 5 different ways.)
Why is that important? According to Steve the Ump (http://goo.gl/SYoS9
), a batter has 4/100th of a second to decide to swing or not. If a right-handed batter swings 1/100th of a second too soon, the ball goes foul. If the batter swings 1/100th of a second too late, the ball goes foul. So when an announcer talks about "split-second decision-making" by a batter, that's how much the second gets split.
(GIF source: Deadspin http://goo.gl/WKPQK