Yesterday, I posted a graph that showed quite conclusively that Fielding Percentage is a meaningless statistic when talking about defensive impact on runs allowed. As commenter CoachOfEarl brought up in the corresponding thread, a slightly more advanced statistic called Range Factor (RF) also has disagreements with UZR. We see this specifically in the case of Adam Jones, who has the best RF in the majors and yet has a -13.1 RngR (the range component of UZR).
Range Factor can be calculated as either RF/9 or RF/G. In this case, I will use RF/9, which is defined as follows:
Range Factor rewards chances. Outfielders who play for fly ball heavy pitching staffs will have high range factors. Infielders who play for ground ball heavy pitching staffs will have high range factors, and vice-versa. This begs a few questions. Does RF measure defense better than Fld.%? Does RF even properly measure range?
With that in mind, I took the quick step of comparing UZR and RF, as well as comparing RngR and RF. The graphs would get squished and distorted before the jump, so please follow the jump and take a look at what kind of correlations we see (or don't see).
First, let's compare UZR and RF.
Interestingly enough, we see a slightly (but not significantly) negative correlation. This isn't terribly surprising, though, given that RF completely ignores the Error, Arm ,and Double Play components of UZR. We understand that, and that's part of Range Factor - it's not designed to answer those questions. Still, we should expect RF to correlate positively with RngR. Let's see if the expectation holds.
Interestingly, it does not. In fact, the correlation is even more strongly negative. I'm not sure I can exactly answer why that is without looking into the backbone of UZR. However, I will say that given the simplicity of RF, I will certainly trust UZR and it's measurement of range, which credits plays out and on the edge of a players zone much more than RF does.
Discussion is welcome and encouraged. What's the next step?