The 20-yard shuttle is the Combine’s approach to measure an athlete’s agility, short-range explosiveness, and lateral quickness. Here’s the description from NFL.com:

The athlete starts in the three-point stance, explodes out 5 yards to his right, touches the line, goes back 10 yards to his left, left hand touches the line, pivot, and he turns 5 more yards and finishes.

As you can imagine, heavier players fare much worse in this metric, and taller players have a slight advantage, too. The best-fit formula from the 2019 Combine using height and weight as inputs is: 4.13 -0.0125 * Height (Inches) + 0.00485 * Weight (Pounds). In other words, for every 20-21 pounds a player weighs, he would be expected to take an extra tenth of a second to complete the drill. Ohio State defensive end Nick Bosa is 6’4 and weighs 266 pounds; that’s a formula for just being average in this drill. But he wound up completing the workout in just 4.14 second, but we would have projected Bosa to take an extra 0.33 seconds to finish, which means he is your 2019 Short Shuttle champion.

This graph shows the expected short shuttle times based on different heights and weights.

The full results below.