re: WTF ever happened to short down chain measurements?

quote:

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In the NFL they have RFID chips in the balls

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Yes, but the accuracy of the location of the ball is probably not as precise as needed for this type of measurement, especially without additional sensors in/on the field (unless we're just assuming close is good enough).

There's also the issue of knowing where the ball is throughout a play, but not knowing where exactly it was when the player's knee went down, for example.