Infield Fielding Range Model
Summary
Model the probability that a ground ball hit into play will lead to an out. Separate models are trained for the probability of an out at different stages of the play given that it has progressed to that stage.
pFielded: probability the ball does not get through the infield
pOutAtContact: probability of out (pOut) at crack of the bat given it was fielded
pOutAtFielding: pOut at fielding time
pOutAtThrow: pOut at time of throw release
pOutAtThrowCatch: pOut at time of throw catch (i.e., fielder at the base receiving the throw)
The main probability of out we feature on the site is derived: pOut = (1 - pFielded) * pOutAtContact. The other pOut values are considered for skill evaluation.
Range +/-: pOutAtContact - pOutAtFielding - How well did the fielder charge the balls or generally get to it faster
Exchange +/-: pOutAtFielding - pOutAtThrow - How well did the fielder make a throw after fielding the ball
Catch +/-: pOutAtThrowCatch - pOutAtThrow - How well did the fielder at the base stretch, scoop, etc. the throw
We use separate models for seasons 2020+ (Hawk-Eye) and prior seasons (Trackman) to account for differences in the tracking systems.
Inputs
This model is based on pitch results from 2019-2023 MLB regular season.
Several inputs refer to an expected fielding location. Imagine a line drawn from the batter to the outfield along the path of the batted ball. The expected fielding location is an estimate of where along that line the fielder would most likely field the ball based on where the fielder was positioned, exit velocity of the batted ball, etc.
The pFielded model inputs include:
Typical fielding time - how long would it take a typical fielder to get to the expected fielding location
Exit velocity
Ground ball first bounce distance from fielder
Ground ball height
The various pOut model inputs differ by where the ball was hit and at what base the out is attempted. In addition to the pFielded inputs, other inputs used include:
Time after contact for the runner to reach the base in question for that play
Distance from fielder's start location to the expected fielding location
Typical throw distance - distance from the expected fielding location to the base where the fielder is attempting to throw
Actual throw distance - distance from the actual fielding location to the base where the fielder is attempting to throw
Time after batted ball contact for the fielder to make first contact with the ball
Time after batted ball contact for the fielder who fielded the ball to throw to the intended base
Arm strength - Statcast
Arm accuracy - Statcast
Time after batted ball contact that the ball arrives to the base it was thrown to
Key Metrics
IFGBOutPM/100 - How many outs has the fielder gained for his team per 100 opportunities