The fastest baseball pitch ever recorded was thrown by Cincinnati Reds left hander Aroldis Chapman on Sept. 24, 2010, and was 105.1 mph. Chapman’s heater topped the mark of 104.8 mph set by Detroit Tigers reliever Joel Zumaya in 2006.
Major league baseball began using radar to measure pitch speed on a regular basis during the 1980s, and the PITCHf/x system was introduced in 2007. While this modern technology has allowed specific numbers to be attached to the speeds of present day hurlers, Sports Illustrated, in a 2013 article listing the most powerful pitchers of all time, put three pitchers from an earlier era at the top of the list.
Nolan Ryan, baseball’s all-time leader in strikeouts, was ranked number three. "Sports Illustrated" cites an instance from 1974 in which a Ryan pitch was measured at 100.9 mph by a laser radar that was about 10 feet from home plate. The magazine goes on to explain that if it had been recorded by the PITCHf/x system, which measures at a standard distance of 50 feet, that same pitch would have registered a staggering number of 108.1 mph.
Bob Feller, number two on the list, pitched from 1936 to 1956, and efforts to gauge the speed of his pitches included the use of army equipment, which after lengthy mathematical computations, had some in attendance claiming a speed of 107.9 mph. On another occasion, Feller pitched alongside a speeding motorcycle, and after several attempts, he was said to have thrown around 104 mph.
The top pitcher on the magazine's list was Walter Johnson, who pitched from 1907 to 1927 and won 417 games. Although the true speed of Johnson’s pitches was never known, one baseball scout summed it up best by proclaiming, “He throws so fast you can’t see ‘em.”