It was no surprise that Justin Verlander of the Detroit Tigers won the AL Cy Young Award for 2011. He was a unanimous selection after a 24-win season in which he won his league's pitching triple crown.
Verlander has many strengths, one being his incredible velocity. He is a starter, but routinely hits triple digits in the late innings of games. How does he do it? Beyond simple arm strength, he has great mechanics that allow him to generate maximum power. He loads up with a very high leg kick, taking his knee well above the waist. That leg drops down into a long and aggressive stride down the mound. But he loses no energy in that leg after it lands. He braces the leg completely like a hitter would and sends all of the energy created by his previous movements up into his hips and shoulders and ultimately the ball. He also loses nothing out to the side in his lead arm. He pulls the left elbow in close to his body to quicken his hip and shoulder rotation and keep his momentum going forward to the catcher.
This is a pitching motion not easily duplicated by young pitchers. The aggressive stride and the braced front leg generate power, but can lead to trouble. The quicker the stride, the quicker the ball must be raised above the level of the shoulders. And the straighter the lead leg, the more the pitcher must work to get his chest and arm out to a proper release point. Rushing down the mound and a high release point can both lead to high pitches, especially at the youth level. But Verlander is a master of his craft and works hard to maintain correct mechanics.
Most guys with the velocity of Verlander throw one or two different pitches and close games. But as if his 100 mph fastball wasn't enough for batters to deal with, he also has a nasty curve and great changeup. Here is a good discussion on Verlander's circle change, a pitch that can be extremely successful at the youth level.