Benefit of the Doubt: Pitchers Can and Do Expand the Zone

by J-Doug on Feb 25, 2011 10:01 AM EST in Pitch f/x Goodies

Author's Note: Having discovered some errors in my data, I have revised the chart above and the following article.

In recent weeks, PitchF/X analysts have noted that pitchers who pitch to the corners get the benefit of the doubt. BtB's own Garik demonstrated how Derek Lowe keeps his walk rate down despite pitching way outside the zone. BPro's Mike Fast showed that the strike zone shifts along with pitch location, and that pitchers take advantage of this effect as they age.

My research corroborates these findings, and also shows that this effect accumulates over the course of an at bat.

The chart above plots expected zone advantage (errant strikes - errant balls / called pitches) against the average location of a pitch relative to the nearest strike zone boundary over the course of an at bat. The trend line* indicates that when the pitcher consistently keeps pitches off but close to the plate, his chances of getting a preferential call on the following pitch increase.

*For those who really want to know, the trend line is calculated using a 5th factor polynomial formula.

The sweet spot (not controlling for pitch type, handedness or other factors) seems to be about ~~0.6 ft. (7.2 in.)~~ 6 inches off the plate. A pitcher who keeps his pitches at that distance from the nearest boundary of the legal strike zone over the course of an at bat will get a free strike every f~~ourteen~~ sixteen called pitches or so.

Conversely, pitchers who pound the zone tend to make things easier for the batter. A pitcher who consistently hits the mark dead center will cost himself a ball for every thirteen called pitches.

This helps explain why pitchers who best paint the corners, such as Mariano Rivera, Livan Hernandez and Derek Lowe, get such a great zone advantage and linear weights differential. It also explains why pitchers who pounds the zone, like Felix Hernandez, do not win the benefit of the doubt.

The evidence is pretty clear that pitchers can, and do, expand the zone.

PitchF/X data originate from Darrell Zimmerman's SQL-based PitchFX database.

Previous Episodes in the Benefit of the Doubt series:

Relievers Who Get the Wide Zone
Starters Who Get the Wide Zone
Pitchers Who Were Squeezed
Batters in the Zone
Lefty Bats Get the Shaft
How Pitch Speed and Movement Affect the Zone
Odd Patterns in Umpire Compensation
The Cruel Umpire
Fuzzy Corners
Strike Zone a Marginal Component of Home Field Advantage
A Tale of Two Hernandezes
Mo and the Wide Zone

Poll

Is it fair that pitchers get extra strikes when they work the corners?

Yes

42 votes

No

47 votes

89 votes | Poll has closed

Tweet Comment 12 comments | 1 recs |

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Comments

Could you explain a little more what the graph shows?

I understand that the vertical axis is Zone Advantage, which I believe is the fraction of extra strike calls (out of all called pitches) that the pitcher would get, but I don’t think I understand what the horizontal axis represents here.

Winner, Beyond the Box Score 32 Predictions Contest, 2009

by Mike Fast on Feb 25, 2011 11:30 AM EST reply actions

I'll give you an example

The first pitch is 0.2 feet outside the closest legal zone boundary. The second pitch is 0.8 feet outside the closest boundary. The third pitch is inside the zone, 0.1 feet away from the closest legal zone boundary. The mean distance from the legal zone boundary would be the mean of 0.2, 0.8 and -0.1, which of course is 0.3. This value is the x axis on the chart.

The chart above indicates that the average zone advantage (extra strikes – extra balls / called pitches) for that third pitch would be ~0.05.

Blogger and Editor, Rational Pastime Blog. Twitter: @RationalPastime.

by J-Doug on Feb 25, 2011 7:10 PM EST up reply actions

Thanks

That makes sense now. Very interesting. Good work.

Winner, Beyond the Box Score 32 Predictions Contest, 2009

by Mike Fast on Feb 26, 2011 9:32 AM EST up reply actions

Robot umps

Now

by Pikachu on Feb 25, 2011 1:30 PM EST reply actions

Very cool stuff, J-Doug. Now, let's speculate :)

Why would pounding the zone be against a pitcher’s interests vis-a-vis the umpire’s call? The inverse is also curious. What’s behind the calls?

One thought is that pitcher’s that pound the zone are more consistent-a smaller deviation of location might create a frame of reference for the hope such that a deviation from that pitcher’s norm is jarring, so it’s viewed as a ball.

On the other hand, pitchers with a wider variation of pitch location create a different frame for the ump. If their deviation is naturally larger it might mask the degree to which pitches are out of the zone.

Of course, I’ve been on the road all week and currently write this on a plane waiting desparately to taxi to the gate, so I could just be losing my mind…

Writer at Beyond the Box Score and tortured Mets fan (is there any other kind?)

by Bill Petti on Feb 25, 2011 11:09 PM EST via mobile reply actions

Two thoughts come to mind

The first one is the one that Mike mentioned, about catcher framing, which I think is probably the best answer.

The second is mere speculation that the umpire might change his reference point (subconsciously or consciously) if a pitcher consistently hits a different spot.

Blogger and Editor, Rational Pastime Blog. Twitter: @RationalPastime.

by J-Doug on Feb 26, 2011 1:47 AM EST up reply actions

This is fascinating.

Also, the poll results are quite interesting.

Rec’d.

I write a Giants blog...Splashing Pumpkins

by Julian Levine on Feb 27, 2011 3:32 AM EST reply actions

Thanks

I expected more people to find it fair, but whatevs.

Blogger and Editor, Rational Pastime Blog. Twitter: @RationalPastime.

by J-Doug on Feb 27, 2011 6:08 PM EST up reply actions

Maybe I'm miss reading something...

But isn’t this just telling us that umpires don’t like to call strike 3 or ball 4? If a pitcher pounds the zone, it’s more likely that he’ll be in a 2-strike count. If a pitcher just threw a pitch off the plate, it’s more likely that he’ll be in a 3-ball count. In either case, the umpire would be likely to reverse the call if the next pitch is in a identical spot near the border of the strike zone. Unless this data is somehow adjusted for count, it seems likely to me that only a fraction of what we’re seeing here is caused by pitcher skill.

VAE PVTO DEVS FIO

by Bhaakon on Feb 28, 2011 10:50 AM EST reply actions

No, it's not just telling you this

As with my older posts I don’t provide the full ordinal logistic model because it’s more than most BtB readers want to read. The effect remains even when you adjust for count and about thirty other variables: http://www.rationalpastime.com/2010/11/tech-notes-pitch-characteristics-and.html

Blogger and Editor, Rational Pastime Blog. Twitter: @RationalPastime.

by J-Doug on Feb 28, 2011 12:08 PM EST up reply actions