On Monday, Baseball Savant released a new defensive metric to help judge outfielders. Jump does exactly what it sounds like — it measures the outfielder’s jump on the ball, defined as, “How many feet did [the outfielder] cover in the right direction in the first three seconds after pitch release?”
Jump is broken up into three components. Reaction measures how much ground the outfielder covers (in any direction) in the first 1.5 seconds after contact, compared to the average fielder. Burst then tracks the distance covered in the next 1.