WAR for Knuckleballers

As you probably know, there are multiple ways to calculate WAR, with our version (sometimes referred to as fWAR) and Baseball-Reference’s version (or rWAR/bWAR, depending on who is citing it) being the two most popular. And, as you probably also know, they can be quite different when it comes to evaluating pitchers. Two years ago, I wrote a couple of posts (Part One, Part Two) explaining why we constructed our pitcher WAR the way we did, and what we see as the pluses and minuses of both systems. Neither system is perfect, and neither system works in every situation, but we feel that using a FIP-based approach to evaluating pitchers is more transparent and more effective for the majority of pitchers in baseball.

But, there are pitchers who routinely outperform their FIP, and the way we do pitcher WAR will systematically underrate those pitchers. The primary group of pitchers who post results that are better than their BB/K/HR rates would suggest are knuckleballers.

Tom Tippett — who now works for the Red Sox — wrote about this extensively back in 2003, so this isn’t a new idea. When Voros McCracken released DIPS 2.0, he adjusted the system to account for the fact that knuckleball pitchers didn’t really fit into the normal trend. Even before R.A. Dickey ever started throwing the pitch, knuckleball pitchers were a well established exception to the norms of FIP. And that means that you don’t want to use standard “fWAR” for pitchers to evaluate Dickey, or any other knuckleball specialist.

Because there are exceptions to FIP, we do not simply display only FIP-based WAR here on FanGraphs. Back in August, we rolled out a few stats that we put under the umbrella of Fielding Dependent Pitching, helping to bridge the gap between a pitcher’s WAR based on his FIP and what his WAR would be if we just evaluated him by runs allowed. Not surprisingly, Dickey’s RA9-wins (which is just WAR based on runs allowed instead of on FIP) over the last three years are significantly higher than his FIP-wins, which is what we call WAR for pitchers here on FanGraphs. By FIP, Dickey has been worth +10 WAR over the last three years. By runs allowed, he’s been worth +15 WAR.

Because Dickey throws the knuckleball, and we already know that knuckleball pitchers outperform their FIP, you should lean more towards RA9-wins for Dickey than FIP-wins. Pitchers like Dickey are why we present both options here on FanGraphs. There simply isn’t one system that works perfectly for everyone. No matter what kind of calculation you use, there are going to be guys who don’t fit perfectly into the model. We added RA9-wins to help show the differences between the two systems, and to give you an alternative way of valuing pitchers who don’t fit perfectly into the assumptions that FIP makes.

You shouldn’t just use RA9-wins for any pitcher who outperforms his FIP, as often times, that’s simply the product of good teammates or some good luck, but you should also know that FIP doesn’t work for every pitcher. Specifically, it doesn’t work for knuckleball pitchers. Eno Sarris helpfully created a custom leaderboard of every pitcher in baseball history who has been noted to throw a knuckler, and as a group, their combined RA9-wins total (1,181) was 206 wins higher than their FIP-wins total (975).

This isn’t just an R.A Dickey or Tim Wakefield thing. Knuckleball pitchers induce weak contact that leads to consistently lower than average rates of hits on balls in play. Because of this, we strongly suggest that you use RA9-wins to evaluate a knuckleball pitcher, not FIP-wins. Dickey has outperformed what our standard WAR suggests, and he’s likely to do so going forward as well. He’s a known exception to the rule. If you want to quote Dickey’s FanGraphs WAR, you’re better off using RA9-wins than FIP-wins. For pitchers like Dickey, it’s a better representation of his real value.



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Dave is the Managing Editor of FanGraphs.


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Dan Rozenson
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Dan Rozenson

Good insights. No stat is perfect.

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