Every time I watch a Red Sox ball game on NESN, as every pitch crosses the plate, projected on the lower right corner of the screen is a graphic that shows the location of that pitch relative to the strike zone, defined as the area over the plate below the armpits and above the knees of the batter when in his natural stance. In fact, a very similar graphic appears in almost every MLB broadcast, be it on the MLB Network, FOX, ESPN, TBS, or otherwise.
In 2006, the league launched the use of PITCHf/x, a technology that tracked the velocity, position, and break of every pitch in real-time. Last year, PITCHf/x was phased out in favor of Statcast, which had initially been installed in all 30 major league stadiums in 2015. Though there have been questions about the pitch velocity being reported by the latter (data suggests that it’s about two MPH higher), the accuracy of the pitches, measured using Doppler radar and high-definition video, is nearly perfect.