The Pastime

I’ve touched on this topic before, but I think I have something new to bring to the table now. In the past, I’ve attempted to evaluate umpires based on the statistics that the pitchers on the mound are putting up. I made some tables, saw a few trends, and that was that.

Given my proclivity for putting things into graphs, I don’t know why I haven’t tried this before.

What I did was simply take the umpire data I pulled from Baseball Prospectus’s statistics, set up a few parameters, and graph the heck out of it.

For instance, here’s a graph comparing umpires’ rates of walks per nine innings and strikeouts per nine innings. The red lines represent the MLB average for BB/9 and SO/9.

How should you interpret that? Use this as a guide:

Generally, umpires with higher strikeout rates and lower walk rates will benefit the pitcher. Those umpires can be found in the lower right-hand corner of the graph. Some examples would be Doug Eddings, John Hirschbeck and Brian Gorman.

Umpires with low strikeout rates and high walk rates will benefit the batter, and they can be found in the upper left-hand corner. Some examples would be Ed Montague, Gerry Davis and Randy Marsh.

—–

The rates that the pitchers put up is only a secondary effect of what the umpires actually do, though. They call balls and strikes. I looked at the percentage of balls and strikes to the total pitches thrown, and whipped up another graph.

Here’s a key to interpreting that one:

Again, some of the same names are showing up at the extremes of the graph. Randy Marsh, Sam Holbrook and Brian Gorman are consistently outliers among their peers.

Something that’s interesting to note is that some umpires, such as Randy Marsh and John Hirschbeck, will appear in the one graph at one extreme to be favoring the batter, and then they will appear in the other graph at the other extreme favoring the pitcher.

I’m not sure why that’s happening, as some umpires are consistent between the two graphs. I’d tend to say that the percentage of strikes and balls graph would be more authoritative, but what’s causing the disparity? Could it have something to do with the pitchers themselves, since K/9 and BB/9 aren’t completely controlled by the umpires, as ball and strike % are? Are some pitchers able to strike people out even though they throw a lot of balls? (like Zito)

It’s something to look into…

This is why you don’t make graphs after midnight… I had a sorting error, and some names were misassigned. It’s now fixed. Sorry.

—–

Now, I want to be clear that while there are definite differences between umpires, I’m not saying there’s anything wrong with that, or that they’re poor umpires. It’s just that not many folks seem to realize that umpiring is highly subjective, and each umpire has their own idea of a strike zone.

I’m working on analyzing umpire data over the past few seasons, to see to what extent umpires tend to call games the same way. If an umpire has a track record of favoring pitchers, then this data is meaningful. If not… then I guess I’ll just keep looking at the numbers, as usual.

This entry was posted on Saturday, January 13th, 2007 at 11:22 pm and is filed under General Baseball, Stats, Opinion, Stat Graphics, Umpires. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.