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Baseball WAR from Prepared Run Components

Combine prepared positional or pitching run-value inputs into the documented FanGraphs-style WAR arithmetic.

  • Formula & worked example
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Calculator inputs

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How to use this calculator

  1. Enter the known values in the units shown. Results update as you type.
  2. Where results are editable, change one to solve backwards. Lock a value to hold it fixed.
  3. Use the worked example to check the method. Reset restores the starting fields.

Private by default

Inputs and results stay in this browser tab. Bookify does not upload or store the values you enter.

Formula and method

Position-player components totaling 41 runs with 10 runs per win give 4.1 WAR.

Position WAR = sum of six prepared run components / runs per win; pitcher WAR = (((league adjusted FIP − adjusted pitcher FIP)/pitcher runs-per-win + replacement level) × IP/9) × leverage + league correction.

Worked example

Enter these known values and leave the other values blank.

Batting runs
20
Baserunning runs
5
Fielding runs
-3
Positional adjustment
-2
League adjustment
1
Replacement runs
20
Runs per win
10
WAR
4.1

Assumptions and limitations

  • Inputs must already contain the relevant run, park, league and replacement adjustments. Baserunning input is in runs, not a count of hits. Pitcher FIP inputs must use the methodology-appropriate adjusted scale, including park/league and RA9 alignment; ordinary published FIP alone is insufficient. Runs per win, replacement level, leverage and league corrections depend on methodology and season; the tool does not fetch current constants or estimate them from a box score. Signed WAR output magnitude is bounded below 10^50 in this implementation.
  • Clear an unknown before solving an available inverse branch, and lock independent known values when comparing measurements. Use compatible units; a one-way score or lookup does not supply an inverse.

Common questions

What does this result represent?

Inputs must already contain the relevant run, park, league and replacement adjustments. Baserunning input is in runs, not a count of hits. Pitcher FIP inputs must use the methodology-appropriate adjusted scale, including park/league and RA9 alignment; ordinary published FIP alone is insufficient. Runs per win, replacement level, leverage and league corrections depend on methodology and season; the tool does not fetch current constants or estimate them from a box score.

Can I work backward from an answer?

Where the captured equation supplies an inverse, clear the unknown and enter independent known values. Rounded scores, one-way outputs and fixed lookup choices do not uniquely recover inputs.

References

Allow signed WAR with finite output magnitude below 10^50; require positive runs per win and nonnegative innings/leverage.

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