What is the calculator supposed to do?

Check out the “About” page for information.

What do all these numbers mean?

Check out our glossary for explanations of what each number means and where it comes from.

What should I use the calculator for?

It’s designed to be used to estimate value for any situation in which actual value numbers are unavailable. You can plug in a player’s projected statistics to get a sense of how valuable he’ll be. You can compare multiple players’ projections, or get a sense of how much a player’s value would change if he took more walks or changed positions. You can find out just how good the players from your video games or other simulations are. Or you can use it as an educational tool and see how much different aspects of the game matter in assessing a player’s worth.

Which calculator should I use?

It depends on what you’re looking for. For position players, Version 2.1 is much more accurate and is adjustable for different run environments, so that’s the better choice for trying to make player projections; Version 1.1.1 uses more basic inputs, so you’re better off using that one for educational purposes or for examining how individual factors shape player value. For pitchers, use Version 1.0.

Is this a new variant of WAR?

No, it’s just a way to estimate how players would rank in other models (the calculator conforms closest to FanGraphs’ WAR, but it should be a reasonable approximation of the other models of value too) without having to do all the heavy lifting of manually replicating the full formulas.

Think of the calculator as like SparkNotes. If you don’t have the time or patience to read the book it’ll give you a pretty good idea of what’s going on, but no one would ever say the simple English translation is better than the actual Shakespeare.

Why don’t these numbers match up with real WAR totals?

For the the position player calculators, the biggest inconsistency stems from estimations of relative offensive value. Version 2.1 uses OPS+ as a substitute for wRC+. As Tom Tango noted, the two are roughly interchangeable, but they are not identical. Most players have small discrepancies between their OPS+ and wRC+.

Version 1.1.1 is based on Bradley Woodrum’s formula for Fielding Independent Offense. FIO was designed to model MLB hitting from 2009-11, but the league has changed in that time. Because offense has declined, the same hitting performance would be relatively better and therefore more valuable in 2011 than in 2009, and way more than in 2001. So the calculator will modestly undervalue a player from 2011, but it would overrate a batter from the Steroid Era. In addition, every ballpark creates a different kind of run environment, so FIO will somewhat overrate batters who play in hitter-friendly stadiums.

For both calculators, the wRC+-to-runs and RAR-to-WAR conversions have also been simplified and do not reflect differing ballpark conditions.

For the pitching calculator, the discrepancies stem from the difficulties of calculating the replacement level; the runs-to-wins conversion is also a little buggy.

I’m working on fixes for all of these problems.

If you have any other questions, problems, or suggestions, please let me know!