WAR and Relievers

Over the weekend, Chuck Brownson did a post over at THT Live, showing the premium that a few teams have been willing to pay for closers this winter, even as the market for nearly everyone else collapsed. Despite a pullback on spending, some clubs still value late inning relievers enough to pay a premium to acquire guys who have had success in that role.

WAR, as you probably know, doesn’t think much of relief pitchers. The very best relievers in the game are generally worth +2 to +2.5 wins over a full season, or about the same as an average everyday player. This has caused quite a few people to state that WAR doesn’t work for relievers, because the results of the metric don’t match what they believe to be true about relief pitcher value. I think it works just fine.

While the quality of their work is very high, the quantity is low, which limits their total value. It’s nearly impossible to rack up huge win values while facing less than 300 batters per season. Yes, each of those batters faced are more critical to a win than a regular batter faced, but this is accounted for in WAR.

The average Leverage Index of a closer is about 1.8, meaning that each plate appearance is about 80 percent more important than an average PA. We give the closer credit for half of that, based on the principle of chaining. Because relief pitchers are mostly fungible, and can move from one role to another if needed, replacing a closer is not the same process as replacing a starter or a position player. If a team’s closer gets hurt, they do not then call up a replacement level reliever from the minors and use him to close out games.

Instead, that replacement level reliever who gets called up from Triple-A becomes the mop-up guy, and everyone gets promoted one slot; the setup guy moves into the closer role, the middle reliever becomes the setup guy, so on and so forth. The high leverage innings are handed to the remaining best pitchers in the bullpen, not the guy replacing the lost relief ace.

Because of this, it does not make sense to give a reliever full value for the credit of his leverage index. That leverage does not belong to him, nor does it go with him when he goes away. Remember, this is Wins Above Replacement, and the guy who replaces a closer is generally a pretty good pitcher. We want to measure the marginal win of a player over what the team would lose if they did not have him, and in the case of relief pitchers, the replacement level is very high.

That a half dozen major league clubs are overvaluing proven relievers does not mean that WAR doesn’t work for them. It’s just an arbitrage opportunity for the rest of baseball.