The DeadArm Era was an era in baseball in which new training techniques came into use.
Techniques that increased pitching velocity at the cost of injuries.
Those ideas were developed by Jim Dixon, refined by Paul Nyman, and then "borrowed" by Tom House.
A few years later, Kyle Boddy of Driveline transformed Flying Open with the Glove from a problem into a way of increasing pitchers' velocity.
While those techniques led to increases in the velocity of pitchers, it did so at the cost of injuries.
Those new techniques worked by overloading the arm, yielding an often quick and easy velocity increase at the cost of a significant increase in the risk of injuries.