Tuesday, November 10, 2009
Criminals of WARPosted by Jeremy Greenhouse
I’m not going to single anyone out, since we’re all guilty of abusing FanGraphs’ Wins Above Replacement metric. But I’ve been seeing cases pop up where it’s getting out of hand. So I’ve set up a few guidelines for how to go about using WAR responsibly. Do not break these rules, or I may call you out.
1. Do not exclude baserunning from a position player’s WAR. I’m sure David Appelman will include baserunning in the next edition of WAR, since it’s so easy to calculate, but the numbers are already out there, so please take the time to go to BP, B-Ref, or BJOL to look up the numbers and tack them on.
2. Do not place undue trust in WAR for catchers. How much of a catcher’s value do you think is in his defense? I’ll give you a hint: it’s a lot. FanGraphs has unfortunately yet to give an effort to quantifying this vital aspect of the game, other than with the positional adjustment. In fact, catchers should possibly be considered a separate group of players with a separate replacement level and therefore be treated as different from all other position players.
3. Do not place undue trust in WAR for pitchers. First off, pitcher defense and hitting aren’t included. This should be righted ASAP. Then there are the more nuanced issues like how leverage is accounted for and the conversion of FIP to runs. Personally, I’d trust the calculations of David Gassko’s pitching runs created or StatCorner’s WAR well before I would FanGraphs’ WAR.
4. Do not cite WAR as a measure of skill. WAR measures production. FanGraphs has a lot more granular data if you’re trying to assess skill. And if you’re going to try to make a projection of WAR, regress each component individually. Also, players with negative WAR still may have value if they excel at a certain skill that can be leveraged.
5. Do not use the linear conversion of WAR to salary to determine what a team should be willing to pay a free agent. Every team has a different scale, depending on that team’s market and where the team is on the win curve. Few teams should pay $5 million for a single win.
I'm sure there are other commandments I'm missing, so feel free to add your own.
Any questions? Feel free to email me.