Probably the most common response to my look at catcher framing was that the pitching staff had to have something to do with the results. I totally agree, but I was curious about how the staff would affect the number.
I thought of three possible “biases” that could change how a pitcher is judged by an umpire: age, reputation (by which I mean success) and early-game wildness. I’m sure there are probably others, and I’m willing to take requests for study.
Anyway, these will be probably be combined into a longer post for Beyond the Box Score later, but I thought I’d post the results as I got them here.
The first test I looked at was by age. I broke down all the pitchers from 2007 into three categories – under 25, between 26 and 35, and older than 35. The age breakdown was somewhat arbitrary, but I wanted to get a young group and an old group, with the hypothesis that umpires were kinder to the older pitchers.
Turns out that young pitchers saw missed calls cost them .37 runs per game, while older pitchers benefited by .23 runs per game. The middle age bracket gained .14 runs per game.
There are a couple of potential flaws to this study that I’ll point out, but I don’t think they’re too serious. First, the release of the Lahman database doesn’t include the Retrosheet ids for rookies from 2007, so I didn’t have a birth year for them – although my presumption is that most will fall in the bottom group. I eliminated them from the study – which will lower both the number of opportunities and the number of missed calls from the young pitchers. If anything, this dampens the actual effect and younger pitchers were hurt a lot more.
Second, there’s definitely a selection bias in play. Older pitchers are those who have pitched well enough to stay around, while younger pitchers may be drummed out of the league under 25. I’m not sure how to correct for that yet, but I might have a better idea when I try to measure how big a role reputation plays.
Long story short, younger pitchers appear to lose at least .6 runs per games to older pitchers based on umpires calls. This may not be solely related to age, but to a combination of factors that are correlated to age, which I’ll try to examine over the next few days.