Major league batters can hit a fastball. Study opposition batting on pitch type, and most pitchers give up the most offense on the fastball. For example the MLB wOBA on the fastball in 2011 is .339. On the change up that drops to .286, the curveball .252. The same holds for Justin Verlander of the Detroit Tigers, except that his fastball is also tough to hit. His fastball delivers a .260 wOBA, his change comes in at .256 and his curve results a .153 wOBA.
Verlander throws a high speed fastball. In 2011, the pitch averages 95.1 miles per hour, putting him in the 93rd percentile. That gives batters problems. There is a speed limit above which the fastball gives hitters trouble. The following graph shows swing data by the speed of Verlander's fastball:
Notice what happens as Verlander's velocity increases. The swing rate goes up, and the contact rate goes down. More swings and misses, which is an excellent result for the pitcher. Strike zone judgment decreases as well. The higher velocity gives batters less time to recognize the pitch as a ball or a strike, and they chase more pitches out of the strike zone. Even if batters make contact on what should be balls, the probability of a good result goes down.
Verlander can consistently hit between 95 and 97 MPH with his fastball. At that speed, he holds the advantage, giving him a fastball wOBA in the 94th percentile in the majors, and helping him finish and flirt with no-hitters.