A FanGraphs WAR Fielding Update

4/23 Update: It has come to our attention that in the switch to Statcast Fielding Runs Prevented (RAA), outfield positional adjustments were being improperly applied. This has now been corrected by zeroing out RAA for each individual position, on a seasonal basis, specifically for use in WAR. The tables below have been updated to include this correction.

Since we launched FanGraphs WAR in 2008, we have used various components of Ultimate Zone Rating (UZR) such as Range, Outfield Arm, and Double Play Conversion to evaluate position player fielding. Today, we’re changing one of those components. Retroactive to the 2016 season, we have swapped out the Range component of UZR for the Statcast metric Fielding Runs Prevented, which is Outs Above Average (OAA) converted to runs above average. The UZR Outfield Arm and Double Play Conversion components of WAR remain unchanged.

We believe the additional data points available in Statcast, such as a fielder’s starting location, help to improve the measurement of a player’s range, especially in situations where players are shifted.

The vast majority of players’ new WAR calculations fall within a +/-1 WAR range of their previous WAR figures. Since 2016, there are 49 individual seasons that have changed by more than one win, and 14 players whose WAR has changed by more than three wins for the entire six year span starting in 2016.

On the leaderboards, we have a new custom field called “Legacy WAR (L-WAR),” which will show the results of the previous calculation for those who are interested in making comparisons.

Below is the list of players who experienced the biggest single season changes, followed by the list of the players with the largest changes since 2016.

Largest Individual Season Changes 2016 – 2021
Name Season Legacy WAR WAR Change
Nick Ahmed 2018 1.7 3.7 2
Carlos Correa 2018 1.6 3.5 1.9
Ender Inciarte 2016 3.1 4.7 1.6
Adam Engel 2017 -0.8 0.8 1.6
Nicky Lopez 2021 4.4 6 1.6
Javier Baez 2019 4.3 5.8 1.5
Francisco Lindor 2021 2.7 4.2 1.5
Jake Lamb 2016 2.4 3.7 1.3
Jordy Mercer 2016 1.4 2.7 1.3
Nick Ahmed 2021 0 1.3 1.3
Andrelton Simmons 2021 -0.5 0.8 1.3
DJ LeMahieu 2017 2 3.3 1.3
Mallex Smith 2019 0.1 1.4 1.3
Fernando Tatis Jr. 2021 6.1 7.3 1.2
Jean Segura 2016 5 6.2 1.2
Travis Shaw 2017 3.5 4.7 1.2
Francisco Lindor 2019 4.7 5.9 1.2
Jonathan Schoop 2016 2.3 3.5 1.2
Max Kepler 2016 1.3 2.5 1.2
Josh Reddick 2018 1.1 2.3 1.2
Brian Dozier 2017 5.1 6.2 1.1
Tim Anderson 2019 3.4 4.5 1.1
Keon Broxton 2017 0.7 1.8 1.1
Manuel Margot 2021 1.4 2.5 1.1
Leonys Martin 2016 2.4 3.5 1.1
Addison Russell 2018 1.5 2.6 1.1
Nick Ahmed 2016 -0.5 0.6 1.1
Starlin Castro 2016 1.3 2.4 1.1
Mike Trout 2016 9.7 8.6 -1.1
Charlie Blackmon 2017 6.6 5.5 -1.1
Christian Yelich 2017 4.6 3.5 -1.1
Paul DeJong 2017 3.1 2 -1.1
Neil Walker 2016 3.6 2.5 -1.1
Yasmany Tomas 2016 0.5 -0.6 -1.1
Brandon Phillips 2017 1.5 0.4 -1.1
Chase Utley 2016 2.2 1.1 -1.1
Jon Jay 2018 0.8 -0.3 -1.1
Harold Castro 2021 0.5 -0.7 -1.2
Matt Kemp 2016 0.8 -0.5 -1.3
Brandon Phillips 2016 0.9 -0.4 -1.3
Didi Gregorius 2019 0.9 -0.4 -1.3
Dustin Pedroia 2016 4.9 3.6 -1.3
Didi Gregorius 2018 4.7 3.4 -1.3
Carlos Correa 2016 5.2 3.9 -1.3
Logan Forsythe 2017 1.9 0.5 -1.4
Zack Cozart 2016 1.9 0.4 -1.5
Didi Gregorius 2017 4.1 2.5 -1.6
Paul DeJong 2018 3.3 1.7 -1.6
Corey Seager 2016 6.9 5.1 -1.8

Largest Changes 2016 – 2021
Name Legacy WAR WAR Change
Nick Ahmed 4.8 11.3 6.5
Javier Baez 17.8 22 4.2
Jonathan Schoop 10.7 14.7 4
Rougned Odor 4.3 7.7 3.4
Adam Engel 2.1 5.4 3.3
Starlin Castro 7.3 10.5 3.2
Francisco Lindor 28.1 31.3 3.2
Tim Anderson 14 17.1 3.1
Ender Inciarte 9.2 12.2 3
Xander Bogaerts 26.8 23.5 -3.3
Marcus Semien 23.1 19.6 -3.5
Paul DeJong 12.8 9.1 -3.7
Charlie Blackmon 18.6 14.6 -4
Didi Gregorius 14 7.7 -6.3





David Appelman is the creator of FanGraphs.

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beastermember
25 days ago

Some nice spring cleaning! Poor Didi….