Mandatory Credit: Denny Medley-USA TODAY Sports

Fun with Arbitrary Endpoints and the Kansas City Royals


If you follow me on Twitter (and if you don’t, feel free to click that link on the right side of the screen to correct the situation), you know that I am a fan of posting statistics using arbitrary endpoints. What’s an arbitrary endpoint, you ask? Basically, anytime a person says “Player X is hitting .400 since July 13th,” or “Pitcher Y has an ERA of 1.38 in his last 5 starts,” that person is using arbitrary endpoints. For evaluation purposes, using arbitrary endpoints is a relatively fruitless exercise. Most of the time, the sample size is too small to draw meaningful conclusions about a player’s true value, so if the specified timeframe shows any deviation from his typical production level, it could be nothing more than random variation.

Essentially, any stat presented with arbitrary endpoints should be taken as nothing more than a fascinating factoid.

The only time a statement like those above may be an exception is if the player made some kind of adjustment right around that date. For example, if a pitcher started using a specific pitch more frequently or throwing it to different parts of the zone, then one could potentially infer that a different performance level may have an actual reason behind it. Even in that scenario, however, future success is not guaranteed. Most of the time, there are just too many factors upon which to base a projection for a player’s future. You are typically much better off using a larger sample size; such as an entire career or a full season’s worth of statistics.

So let me preface the following by repeating: Stats presented with arbitrary endpoints are for entertainment purposes only.

Without further ado, here are some numbers you will hopefully find as interesting as I did:

- In the month of August, Billy Butler posted a wOBA of .393, while having a higher walk rate (11.6%) than his strikeout rate (10.9%).

Justin Maxwell, in the last 30 days, has a wRC+ of 133, which is higher than that of Giancarlo Stanton (132), Justin Upton (124), Jay Bruce (96), and Wil Myers (90).

- During August, Alex Gordon drew 3 walks in the entire month. Salvador Perez has drawn 3 walks in the last 7 days.

- Over the last 30 days, Perez has a line of .293/.341/.537, which gives him the highest OPS among AL catchers during that time. It’s also better than last year’s NL MVP, Buster Posey.

- Alcides Escobar has 5 infield hits in the last 14 days, which is the exact same number of infield hits collected by Billy Butler in that same period.

- In the last 30 days, Ervin Santana has an ERA of 4.96. Some of the pitchers who posted higher ERAs: CC Sabathia (5.21), Adam Wainwright (5.81), Francisco Liriano (5.94), and Felix Hernandez (6.42).

- Over the last 30 days, Danny Duffy has a K/9 rate of 9.45, which is the 6th best number in the AL during that timeframe.

- The Royals bullpen has 4 of the top 9 strikeout percentages among AL relievers in the last 30 days: Will Smith (47.6%, and he just struck me out as I typed that), Greg Holland (41.9), Luke Hochevar (38.3), and Kelvin Herrera (32.8).

- Aaron Crow has a walk rate of 7.27 BB/9 over the last 30 days. Amazingly, there are 7 other relievers in baseball with at least 5 innings pitched during that time who have a higher walk rate.

- Royals’ relievers, as a whole, have an ERA of 1.35 in the last 30 days. The next closest AL team, the Rangers, have an ERA of 2.86.

- The Royals’ rotation posted an August ERA of 3.73, which was the 3rd best number in the AL during that month. They did this despite being tied with the 2rd worst K/9 (6.37).

- On offense, the Royals have put up a wRC+ of 91 in the last 30 days. Only 3 AL teams (Blue Jays, Indians, and Mariners) have been worse in that category.

- Jamey Carroll, during his 31 plate appearances in Kansas City, has amassed a wRC+ of -45. If you’re not familiar with that stat, 100 is average, so anytime you see a negative number, something has gone horribly, horribly wrong.

- As bad as Carroll has been, keep this in mind: Elliot Johnson’s final 18 plate appearances with the Royals produced a wRC+ of -93.

Just remember, kids: use those arbitrary endpoints wisely.

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  • jimfetterolf

    Arbitrary beginning points are handy, as you say, if something substantive happened to change a player’s game, Bubba getting Lasik, Brett fixing the atrocious swings of Hos and Moose, a player getting dinged with a nagging injury. Just part of the ongoing weighting used to fine tune career stats down to the moment.