In 21st-century baseball, digital devices monitor heart rates, skin temperature — they even track fielder's movements, all part of the exponential data explosion used to determine batting orders, pitching changes and defensive shifts. As part of the union's agreement to approve devices, 40-man roster players have the right to limit who sees the data. Don't tell them numbers," he said. In baseball, it is being used along with velocity devices. With every team looking for an edge, these devices have become as common as pine tar rags.

Source: ABC News April 01, 2017 18:43 UTC