In Search of the Veteran Benefit of the Doubt

On some level, people have understood pitch-framing for a long time. Catchers have long been taught to try to reduce their movement with the pitch on the way, and there were good framers before there was good framing analysis. But before people started really talking about the various good and bad framers, there were some other popular theories regarding the variations in called strike zones. Among them was that home-plate umpires would be tough on rookie pitchers, while to veterans they’d extend the benefit of the doubt. For so long, this was just kind of accepted, even among players, and it’s not like there’s ever been an abundance of data to analyze. That is, until PITCHf/x, which continues to revolutionize things years and years after its launch. We’re all revolutionaries!

Because you can probably see where I’m going, I’ll spare you more needless introduction. In short, I wanted to go in search of the veteran benefit of the doubt, now that we have a full six years of pretty reliable PITCHf/x data. Really, I wanted to go in search of age bias, and I figure if such a bias exists, it shouldn’t be too hard to turn it up. All the information I needed, I got right here on our own leaderboards. And it turns out there’s definitely been something interesting going on. It’s been subtle, but overall it’s been present.

The numbers you’ll see are my own home-spun metric, which I calculate using our own data and which I’ve written about several times before. Here I’m choosing to call it Diff/100, which is the difference between strikes and expected strikes per 100 approximate innings, relative to the league average. With FanGraphs’ PITCHf/x data, it’s possible to calculate how many strikes a pitcher should’ve ended up with. A negative total suggests a smaller called strike zone, while a positive total suggests a bigger called strike zone. According to the theory, we should see inexperienced pitchers get negative totals, while veteran pitchers get positive totals.

I decided to analyze season-to-season by splitting all the pitchers in MLB into groups. For each year from 2008 through 2013, I collected numbers for rookies, guys up to 25, guys between 26-30, guys between 31-35, and guys 36 or older. The groups are somewhat arbitrary, but the arbitrariness shouldn’t mask any meaningful effect. Rookies threw about a fifth of all pitches. Guys between 26-30 threw almost half of all pitches. Guys 36 or older accounted for just 6% of all pitches, but the samples still numbered in the tens of thousands of pitches. At this point I feel like I should just get to the table.

Here’s everything. The numbers are in Diff/100. That’s the number of strikes above or below average relative to the expected number per 100 innings, more or less. Just typing that feels like a mouthful but I promise it’s actually pretty simple.

Group 2008 2009 2010 2011 2012 2013 Average
Rookies -1.2 -4.5 -3.5 -7.8 -5.3 -4.5 -4.5
Through 25 -5.3 -2.6 -3.2 -4.0 -3.5 -2.6 -3.5
26-30 -1.0 -1.4 -0.5 -3.0 -0.1 -0.5 -1.1
31-35 7.4 4.8 5.8 3.9 5.5 7.7 5.9
36+ 15 14 14 20 4.8 7.6 13

Right away, you probably looked at the last column, and right away, you probably noticed a bit of a trend. The numbers get more positive as the pitchers get older. The trend basically holds every year, save for 2008, when rookies pitched to a slightly bigger zone than pitchers 25 or younger. The last two years, there’s been no real difference between the second-to-last group and the oldest group, but there has been a difference between those groups and the younger groups.

What the table suggests is that veterans have gotten the benefit of the doubt, compared to younger pitchers. It’s a fairly small effect, considering how many pitches are thrown over an average 100 innings, but it looks like an effect really is there. On average, between rookies and pitchers 36 and older, you’d expect from these numbers an ERA advantage of about 0.20 in the older pitchers’ favor. That is, everything else being equal. That’s roughly the value of 17 extra strikes per 100 frames.

But I have a different, if related theory. My belief is that pitchers with good command will be able to throw to more favorable zones than pitchers with worse command. Catchers will be able to catch them more easily, and umpires will be less often taken by surprise by location. Rookies, probably, will have the worst command, since they’re by and large untested. Then the older groups will be selective for guys with command good enough to stick around, even after their stuff gets worse. Within the oldest group, you have guys pitching in the majors, and you probably don’t have many guys throwing 95 miles per hour. So they have to be good at something else, and it’s probably location. That might well explain what’s observed in the table. It might look like the benefit of the doubt, but really, it’s just easier to get calls if you put the pitch around where its target is.

So there are at least two possible explanations. But there’s only one truth: at least over the past six years, older pitchers, on average, have thrown to more favorable called strike zones than younger pitchers. It’s a relatively small effect, but it’s a tough effect to deny. And regardless of whether it’s because of command or because of umpires giving the benefit of the doubt, it’s still different pitchers throwing to different zones in the same game. A lot of people have a lot of trouble with that, as an acceptable reality. Other people don’t really care, and it’s not like this is going to resolve itself overnight.

Later, I figure it’s worth doing a similar study for hitters instead of for pitchers, since there are also ideas out there about veteran hitters being given a little more leeway. And with hitters, we wouldn’t have to worry about thinking about pitcher command, since you’d expect that would all average out. The results promise to be interesting, or not interesting at all. But they’re going to be published! Unless something terrible happens.




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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.


22 Responses to “In Search of the Veteran Benefit of the Doubt”

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  1. agam22 says:

    I do think the biggest thing going on here is survivor bias. I guess there isn’t really enough data yet, but in a few years the best way of seeing this I think would be to look at just the pitchers who make it to 36 and see how the numbers change throughout their careers

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    • dixie_flyer says:

      I agree with the comment wrt survivor bias; in fact, this article is almost meaningless and the data does not “prove” the conclusion that was drawn.

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      • LK says:

        Did you read the article? Because it seems pretty agnostic as far conclusions go, and mentions survivor bias explicitly.

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        • HaileeDunphyvin says:

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      • tz says:

        Not at all meaningless. The article is caveated, as LK notes, and is an interesting read.

        In a way, maybe Jeff is crowdsourcing the tweaks to this analysis to a knowledgeable audience, making this a very symbiotic exercise.

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  2. Iron says:

    Excellent post and looking forward to the hitter study. Pitchfx is just a damn wonderful thing.

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  3. Mike Green says:

    I noticed the significant difference in the 36+ figures for 2008-11 and 2012-13. Perhaps this results from more league monitoring of umpires with Questec and its successor system.

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  4. RC says:

    ” It’s a fairly small effect,”

    20 extra strikes over 100 innings doesn’t seem like a small effect to me.

    Doing a bit of googling, I’m finding the value of switching a ball to a strike to be about .15 runs. That’s 3 runs per 100 innings, or 5-6 runs for a typical starter’s season.

    That’s an average of half a WAR per year for older starters over younger ones, just because of that bias. That’s HUGE.

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  5. Tim says:

    it’s still different pitchers throwing to different zones in the same game.

    You might want to check that by looking at starters and whether there’s a difference in old/old, old/young, and young/young matchups. I have a sneaking suspicion that some of this effect is coming from large zones in games with two veteran starters.

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    • harry says:

      this was my thought as well when i read this sentence. I would find it very interesting to see if there is a difference bw zones for 2 ptichers of vastly different experience in the same game.

      Also for relievers. Does the zone change when an experienced reliever comes in for an inexperienced starter in the same game and visa versa.

      Probably not easy to figure out, but would be interesting

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      • jruby says:

        This is interesting, and seems to match what I’ve observed. With two veterans, you get the umpires giving each pitcher the benefit of the doubt wherever either one wants to throw it.

        When it’s a veteran against a rookie, though, the story seems to go like 1) rookie gets squeezed a little, 2) veteran gets benefit of the doubt in his favorite spot, and 3) the umpire starts to give the rookie some leeway, but *only in that spot*, whether the rookie works there a lot or a little.

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  6. cass says:

    We need a measurement for command.

    Perhaps something like the percentage of balls thrown in 3-0 counts? I know that’s control, but at least we can be almost certain the pitcher is trying to throw a strike. Unless it’s an intentional walk in disguise.

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    • The Stranger says:

      I think the problem there is that the Diff/100 contributes to balls thrown, BB%, etc. So you’re trying to isolate a variable by using something that’s dependent on that variable by an unknown amount. Until PITCHf/x tells us where the catcher is setting up, I think we’re stuck.

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  7. Chris from Bothell says:

    You alluded to your own pitch framing research but didn’t mention it further. Shouldn’t this look at pitcher zones also be plotted against the other half of the battery?

    I’d be curious to see if there’s trends when a vet pitcher is pitching to a rookie catcher, or to see if a vet catcher is significantly helping rookie pitchers get better calls than they “should”, and so on.

    Same for how each of those pitcher groups do with poor pitch framers v. excellent ones.

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  8. Mr Punch says:

    As an older fan, I’d say that your suggested explanations miss a nuance that we used to hear about – or perhaps it’s a version of your “command” hypothesis. This is the idea that a veteran pitcher could establish “his pitch,” a spot he could hit reliably on which he’d get the strike call even though it wasn’t quite in the zone. (Mel Stottlemyre was a famous case.) Dennis Eckersley’s commentary often assumes this, I believe, although it’s presumably less prevalent than it used to be.

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  9. siggian says:

    Another question is how the veteran pitcher vs young hitter plays out agains the young pitcher vs the veteran hitter. If there is a “veteran presents” benefit happening, you’d think that veteran hitters would also get a bit of a bounce too.

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  10. tduren says:

    The effect could be due to less velocity. I have always observed that the harder a pitcher throws, the smaller the strike zone. Generally, over 36 pitchers do not throw as hard as rookies.

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