The technology is not as far off as it may seem. From 2006 to 2017, every MLB stadium had a system called PITCHF/x to track pitches. Starting in the 2017 season, PITCHF/x was replaced by a system called TrackMan.
In PITCHF/x, high-quality cameras were positioned in precise locations in each stadium. A central computer analyzed the video from each camera in real time to track the exact location of the ball in a 3D model of the ballpark. This data was used to calculate the precise speed and location of every pitch, as well as the type of pitch. The data was displayed in real time in stadiums, as well as on broadcasts to animate the strike zone in real time. PITCHF/x also powered the online Gameday webcasts seen on the MLB and ESPN websites and apps. The most cited shortcoming of PITCHF/x was its inaccuracies when measuring breaking balls (curveballs, sliders, etc.) and spin rates. This has been widely attributed to the way PITCHF/x used and accounted for the Doppler effect — the changes in light, sound and radio waves as an object moves closer or further away from you. (It’s the same reason an ambulance siren goes up in pitch when getting closer to you, then gets lower when it is travelling away from you.)
TrackMan powers Major League Baseball’s Statcast. In addition to tracking every pitch in a more precise way, the system tracks every object in the field of play. The system has been used to track sprint speeds of outfielders, catch probabilities, exit velocities, launch angles and more. TrackMan works by using even more cameras and sensors in all 30 MLB stadiums as well as 80 minor league baseball stadiums to pinpoint every ball, player and more. Despite the revolutionary advances TrackMan has allowed fans and teams, it still has problems which must be solved before replacing home place umpires. TrackMan also has issues with the Doppler effect and has been found to be susceptible to interference and potential sabotage by radio frequency waves. Even rain affects the accuracy of the system.