This is a fascinating. At least to me. It's generally accepted that pitchers today don't throw any harder than Bob Feller or Walter Johnson. Why? I mean, athletes in other sports have gone faster over the last 50 years, why not pitchers?
Turns out that a 100 miles per hour fastball realy is about the maximum speed the human arm can throw. The article doesn't really talk about the physics, but of course if your hand has to be moving 100 mph at the release point to throw the ball 100 mph. It's just not possible to make one's hand move faster than 100 mph. Ligaments, tendons, etc., start to snap. And unlike, for instance, tennis, there's no equipment out there to help pitchers. It's just them and the ball. Fascinating.
On the other hand, the story of the legend mentioned, Steve Dalkowski, is just really sad.