In Search of the Veteran Benefit of the Doubt, Part Two

A little earlier, I played around with some strike-zone data. There’s a theory out there that umpires are more willing to give veteran pitchers the benefit of the doubt when it comes to called strikes. I wanted to investigate that, and sure enough, I was able to turn up a modest effect related to age and experience. However, my suspicion is that this has less to do with doubt benefits, and more to do with pitcher command. It makes sense that more experienced pitchers would be better command pitchers, and it makes sense that better command pitchers would end up with a little called-strike benefit given what we understand about good and bad pitch-framing, and so on. It’s something that could be investigated further, and I’ll think of what I did as a simple starting point.

Now, if we’re going to look at pitchers, we should also look at hitters. Just as there’s a theory that veteran pitchers get the benefit of the doubt, there’s also a theory that veteran hitters get the benefit of the doubt, in the opposite direction. In short, a lot of people believe that umpires are biased in favor of age and experience. I don’t know where this comes from, but enough people have repeated it that it’s worth a quick look with the numbers we have available. Once again, what follows isn’t exhaustive, but once again, it should get us started. If there’s any kind of major effect, this study should be able to find it.

The methodology is all the same as before. It leans on season-to-season PITCHf/x data from 2008 through 2013. Based on what we have here, we know how many strikes hitters have seen. Based on what we have here, we know how many strikes hitters should have seen. As with pitchers, for the sake of consistency, I’m going with Diff/100, which roughly corresponds to the difference between strikes and expected strikes per 100 innings, relative to the league average. It’s awkward to use an innings denominator when looking at hitters, but it’s also awkward to force a plate-appearance denominator since different hitters can have such different approaches. For the average hitter, the denominator is equivalent to a little more than 400 trips to the plate. I’m just going with Diff/100 so the numbers can be easily compared to the numbers for the pitchers.

You’re going to see data for five groups, for each of the last six years:

  1. rookies
  2. hitters up to 25 years old
  3. hitters aged 26-30
  4. hitters aged 31-35
  5. hitters at least 36 years old

Rookies have accounted for about 13% of plate appearances. The elders have accounted for about 7%. Players 26-30 have accounted for about 45%, making for the most highly-represented sample. Rookies, incidentally, have struck out 2.8 times for each walk, while the elders have struck out 1.9 times for each walk. That ought to surprise no one.

An important point: for pitchers, a positive Diff/100 is good, because it means more strikes than expected. For hitters, a positive Diff/100 is bad, for the same reason. A positive Diff/100 suggests a bigger called strike zone, which works to the hitter’s detriment. If the theory about veteran hitters were to hold true, we’d expect younger hitters to show a more positive Diff/100 than older hitters. Here, now, is all the information.

Group 2008 2009 2010 2011 2012 2013 Average
Rookies 4.5 4.2 8.0 5.1 7.5 6.2 5.9
Through 25 4.2 4.5 6.9 3.8 4.4 5.3 4.9
26-30 1.9 -0.6 2.5 -1.2 0.1 1.2 0.6
31-35 -1.0 -2.4 -3.9 -3.6 -0.8 -2.2 -2.3
36+ -7.3 -4.5 -8.8 -0.6 -5.9 -3.8 -5.2

And there you go. As with the table for pitchers, the most important column is the last one, which averages the previous six. And as with the table for pitchers, this table for hitters shows something of a trend that correlates with age. Rookies have gotten more strikes than expected. The oldest hitters have gotten fewer strikes than expected. There’s a small decrease with each successive group. The effect, again, is relatively small, but at least it looks like there could be something there.

What the table suggests is that veterans have gotten the benefit of the doubt, compared to younger hitters. To only a very small extent, however. The difference between rookies and guys 36+ is about one extra strike per 79 called pitches. The difference between rookies and guys 31-35 is about one extra strike per 107 called pitches. On average, there are about 2.1 called pitches per plate appearance, so the shown difference between rookies and guys 36+ would be about one strike per 38 trips, or about 16 strikes per 600 trips. That works out to a difference of about two runs, over a full season. That’s comparing either extreme.

And now for the alternate hypothesis. I think the explanation for the trend with pitchers is that older pitchers have better command. Hitters, of course, don’t have “command” in the same sense, but I wouldn’t be surprised if this were related to discipline. While hitters can’t control where the pitches are going, guys can have different commands of their zones, and perhaps with experience hitters become more able to adapt to the strike zones as they’re called. This analysis treats all pitches in the zone as equals, and all pitches out of the zone as equals. Veteran hitters might lay off pitches less likely to be called strikes. Younger hitters might swing at a different distribution of pitches that would only really reveal itself through a deeper PITCHf/x analysis. Again, this is a starting point.

I started out investigating whether veteran hitters get the benefit of the doubt from home-plate umpires with regard to the called strike zone. The data is more supportive of the hypothesis than non-supportive. That said, there could be an alternate explanation that once more has to do with a kind of survivor bias. And regardless of the explanation, the observed effect is so small as to be imperceptible over a given plate appearance, or even over a stretch of them. It might well be that veteran hitters are treated a little more nicely than inexperienced hitters, overall as a group, but when it comes to any given controversial ball or strike call, the call presumably would’ve been made because of something else.



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Jeff made Lookout Landing a thing, but he does not still write there about the Mariners. He does write here, sometimes about the Mariners, but usually not.


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tz
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tz
2 years 5 months ago

Finally, a POSITIVE hitter aging curve ;)

byosti
Guest
byosti
2 years 5 months ago

all a part of Ruben Amaro’s plan.

HaileeDunphyvin
Member
HaileeDunphyvin
2 years 5 months ago

my buddy’s step-mother makes $78 /hour on the laptop . She has been unemployed for 8 months but last month her paycheck was $15073 just working on the laptop for a few hours. visit here…… http://iop.li/8wv

B N
Guest
B N
2 years 5 months ago

Sweet. I didn’t realize we had word problems on here. If Hailee’s buddy’s step-mother’s former room mate earned $15073 on her last paycheck, and she makes $78/hour, how many hours did she work?

Apparently, about 193.24359 hours. Which is oddly specific, when you think about it. I know she’s been out of work 8 months, but you’d think she could find a place that would pay in whole hours.

That’s also far more hours than I would classify as “a few.” For example:
Buddy: “Hey, could you help me move apartments? It will just take a few hours?”
Friend: “Sure, no problem!”

(193 hours later)

Friend: “Help, I am trapped in a forced labor camp. I have been forced to work for over 8 days straight on a laptop, with my only company an out-of-work step mother. Please, anyone, can you hear me?”

The Stranger
Member
2 years 5 months ago

Does PITCHf/x track who the umpire is? It would be interesting to see if there are some umpires for whom this trend is more pronounced. That would go a long way towards showing an actual “benefit of the doubt” and not just survivor bias.

I’m more inclined to see a real thing here than with pitchers, though. It’s easier to imagine the pitcher influencing the strike zone (with the catcher’s help) than the hitter.

The Stranger
Member
2 years 5 months ago

What I mean is, I can imagine a pitcher with good command hitting his spots and inducing an umpire to call strikes by doing so, and it makes sense that older pitchers would be more likely to have that skill. Whereas it’s harder to imagine hitters doing something comparable (though not impossible), so it’s more likely that they’re just getting the benefit of the doubt.

Wil
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Wil
2 years 5 months ago

I wonder if the increased strike numbers to rookies are also a result of pitchers simply “challenging” rookies, while pitching more carefully to veterans.

Hank G.
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Hank G.
2 years 5 months ago

The stories I’ve heard have been more along the lines of it being exceptional hitters getting the benefit of the doubt, as in “Mr. Hornsby will let you know when you throw a strike.”

DUTCH4007
Member
DUTCH4007
2 years 5 months ago

Agreed I have always heard the benefit goes to “good” not “old” hitters. Could you do the number using categories based wRC+ rather then age? I know this might mot be perfect either as I would guess there is a lag time between actual performance and reputation, an aging great plays reputation might last longer then his skill.

Since reputation is what we are trying to isolate. What if you did three categories any one who has played in an all-star game, no all-star games non rookie and rookie. If you wanted four categories separate multiply all-star appearances.

Go Nats
Guest
Go Nats
2 years 5 months ago

My favorite hitter in this vein was that tragedy called Nick Johnson. I was begging for a full season out of him for several years. But, it did seem umpires usually gave him the benefit of the doubt most of is injury riddled career.

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