From Washington Post:
Greg Maddux should be one of the most-copied pitchers ever, yet few would even know where to begin, because he seldom opened up about what he believed about pitching and why.
First, Maddux was convinced no hitter could tell the speed of a pitch with any meaningful accuracy. To demonstrate, he pointed at a road a quarter-mile away and said it was impossible to tell if a car was going 55, 65 or 75 mph unless there was another car nearby to offer a point of reference.
“You just can’t do it,” he said. Sometimes hitters can pick up differences in spin. They can identify pitches if there are different releases points or if a curveball starts with an upward hump as it leaves the pitcher’s hand. But if a pitcher can change speeds, every hitter is helpless, limited by human vision.
“Except,” Maddux said, “for that [expletive] Tony Gwynn.”