Monday, February 01, 2010
More on WARPosted by Jeremy Greenhouse
Earlier this year, it seemed like every other week FanGraphs was improving its stats section. So I’m anxious to see what David Appelman has in store for the new season comes, as I’m sure his projects have been building up. But first, I had some thoughts on the already-existing WAR.
My main philosophical problem with Fangraphs’ WAR (fWAR) is that relievers are given extra value for having pitched in high-leverage situations. Personally, I don’t understand why we use a pitcher’s actual leverage index and chain from there. Why not just start and end with the deserved leverage index?
My new and unrelated idea is to replace linear weights as the primary metric used to calculate WAR with WPA/LI. I proposed this, and Colin Wyers disagreed. Wyers either doesn't follow my thought process, or I'm wrong. So I felt I should explain my rationale.
For pitchers, FanGraphs has decided not to include defensive data. I propose that pitchers should be evaluated based on WPA/LI with defensive adjustments based on UZR. Rally’s WAR (rWAR) essentially follows this method by tallying a pitcher’s runs allowed and adjusting for defense with Total Zone. I'm uneasy using rWAR for pitchers, for the simple fact that I can’t get over an advanced metric using RA or ERA. But WPA/LI as the basis for rWAR would serve the same purpose and would be much more accurate in measuring a pitcher's actual contributions. Also, for relievers, WPA/LI adjusts for the game state in which the reliever enters the game, which I think is a huge plus.
As for hitters, for which fWAR and rWAR both use basic linear weights, WPA/LI is just better in my opinion, in that its weights are "perfect." WPA/LI has dynamic linear weights, so to speak.
I feel WPA/LI should be the starting point, though far from the end point. WPA/LI has its problems, since the current version doesn’t distinguish between hitter, baserunner, pitcher, and defense. The hitter and pitcher are assigned equal responsibility for all events. The data is available to calculate WPA/LI for baserunners and defenders, but it would be exceedingly difficult to do so. Nevertheless, WPA/LI is just a step up from basic linear weights in that it accounts for the game state. It's going to take a while for someone to develop a WPA/LI-based WAR, but I have a feeling that WPA/LI is the future.
Any questions? Feel free to email me.