Arm Strength
Definition
On an individual play, Arm Strength is defined as the maximum velocity of any throw made by a fielder -- with the max velocity always being at the release point, due to physics. It can be used to evaluate outfielders on attempted assists, catchers on stolen base and pickoff throws, and infielders on throws across the diamond. Fielders -- especially outfielders -- often get a running start before throwing. As a result, the velocity on their throws can exceed that of pitchers, who throw to batters from the mound.
Putting a quantifiable number on the strength of a fielder's arm helps to evaluate the effectiveness of that arm. However, arm strength is not the only component of a good throw. Along with velocity, the accuracy of the throw is very important, as is the trajectory. A 90 mph throw from the outfield that bounces three times will inevitably lose speed each time it hits the ground.
Additionally, Statcast provides an Arm Strength leaderboard on Baseball Savant, displaying the fielders with the highest average arm strength on "max-effort" throws.
The Arm Strength leaderboard includes rankings for both outfielders and infielders, going back to the first season of Hawk-Eye tracking data in 2020. Because each position requires different amounts and types of throws, a player's average max-effort arm strength is determined differently for each position, with varying numbers of throws required to qualify for the leaderboard.
Here is how the Arm Strength metric is calculated for each position:
- First basemen: Average arm strength of top 1% of throws (minimum 100 throws to qualify for Arm Strength leaderboard)
- Second basemen, third basemen and shortstops: Average of top 5% of throws (minimum 75 throws to qualify)
- Outfielders: Average of top 10% of throws (minimum 50 throws to qualify)
The Arm Strength metric includes both an overall number for every fielder, as well as arm strengths split by each position group and individual position.
Catcher Arm Strength is displayed separately within the Catcher Pop Time leaderboard. Similar to position players, the catcher arm strength metric is calculated as the average of catchers' max-effort throws, which is defined as their top 10% of throws.
In A Call
"throw velocity," "He made a 100 mph throw"