I have to say, we’ve really loved watching how the Win Value stats we introduced a few weeks ago have taken off around the blogosphere. It was definitely a project we were excited about, and I’m personally quite pleased that you guys have responded to them as well as you have.
I did want to mention a couple of things, though. Yes, win values for pitchers are coming. We’re actively working on making sure we have the most accurate formula we can for calculating them, and because of things unique to pitchers, they simply aren’t as straight forward as hitter win values. There’s the starter/reliever issue, how leverage should be handled, the DH issue between leagues, and the various issues of what is within a pitcher’s ability to control and what could be considered outside influence. When we introduce the pitcher Win Values, though, we’ll definitely walk through them step by step, as we did with the hitters, and try to make them as transparent as possible.
I know that a lot of you are already calculating these win values on your own as well, using various inputs, especially in terms of projecting how teams will fare in 2009. That’s great, and definitely one of the fun things you can do with a Win Value system. This isn’t intended to dampen your enthusiasm for these metrics at all. However (and I know you could feel that word coming), I think there are a few things we should mention in regards to adding up Win Values for a roster.
First off, wins aren’t entirely linear. A player who is projected as a +2 win player won’t have the exact same impact on a 60 win roster that he would on a 95 win roster. There’s diminishing returns that start kicking in, and there are only so many at-bats and high leverage innings to go around.
And, of course, the specifics of the player’s skillset interact with his environment, so a change in environment could change his value. For instance, taking a flyball pitcher and sticking them in front of the worst outfield defense in the world is going to have an impact on the value of a +2 win pitcher. By just adding up individual player win values, we lose these contexts, and they matter.
Also, as many of you have noticed, the position adjustments don’t add up to zero. For each individual player, this isn’t a problem. However, the fact that the AL has a DH and the NL doesn’t makes it an issue when trying to compare teams across leagues. It’s not that hard to adjust for, but it shouldn’t be left out of the discussion if you start doing Win Value evaluations or projections for all 30 major league clubs.
Just a few things to keep in mind as we all bask in the awesomeness of the availability of these metrics.
Dave is the Managing Editor of FanGraphs.