Using Pitch F/X to Determine an Umpire's Strike Zone

by Jeff Zimmerman (TucsonRoyal) on Apr 20, 2009 5:37 PM EDT Comment 16 comments

With Pitch F/X there has been quite a bit of work on looking at different pitchers. I decided to extend the work I did on umpire scoring and link that information to pitch F/X. I used the standard strike zone of -1, 1 for the width of home plate and then adjusted the batter's height to the vertical standard of 1.5 to 3.5. Here is a spreadsheet with the percentage of pitches that each umpire called strikes and ball and and how they compare to the standard strike zone (-1,1 to 1.5,3.5). I drew the cutoff line to include umpires with more than 1456 called balls and strikes (The bottom 11 umpires called 918 or less strikes).

Then, I ask for some help in determine what percent of pitches in a zone should constitute the area that balls and strikes are normally called by the umpire. I decided to take their advice and use the value of 90%. I increased or decreased the standard strike zone in equal increments until 90% of the pitches were strikes or balls. Here is the dimensions of the strike zone (along with the percentages of correct calls with the normal zone). I added these two differences together to get the amount these areas overlap (inconsistency of the umpire).

Average value for:	Value
% of strikes called strikes	78.8%
% of balls called balls	85.4%
% correct	83.2%
Adjustment for Strikes (90% zone)	0.15
Adjustment of Called Balls (90% zone)	-0.09
Combined Adjustment Distance	0.24

Here is an image of the normal strike zone (black) along with the actual zone where strikes are called strikes (inside the red square) and the zone when balls are called balls(area outside the yellow box) 90% of the time.

After that, I went ahead and determined the zone for each individual umpire (on previously link spreadsheet).

Finally for a few of umpires, I have looked to find find how their strike zone compared to a centered zone. Basically, do they call the a little lower or outside. I having a tough time find a good to determine this zone, but am making progress, I will update these values as I figure them out and will let everyone know when the values are complete.

I went ahead and linked the previous data I had on umpire effects to the Pitch F/X, but I am wanting to do the R/G, K/G, etc for the same seasons I did the pitch F/X analysis. I want to include park factors and finally get an umpire factor for each umpire that can be applied to each pitcher to see how much the home plate umpire effected their season. As always thanks for your time and and I am open to comments and suggestions.

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Shouldn't the average "Adjustment of Called Balls (90% zone)" be negative?

All the individual values are.

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by bs.uf15bosox9bears23 on Apr 20, 2009 6:07 PM EDT reply actions 0 recs

And what is the br_ing column on the sheet?

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by bs.uf15bosox9bears23 on Apr 20, 2009 6:10 PM EDT up reply actions 0 recs

Base Runners per Inning

by Jeff Zimmerman (TucsonRoyal) on Apr 20, 2009 6:23 PM EDT up reply actions 0 recs

Ohh....

That makes sense now.

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by bs.uf15bosox9bears23 on Apr 20, 2009 7:02 PM EDT up reply actions 0 recs

Yes - corrected

by Jeff Zimmerman (TucsonRoyal) on Apr 20, 2009 6:22 PM EDT up reply actions 0 recs

Hmm...

For all the complaining on both sides of the O’s-Sox series, the umps were all aroung 82-83% correct – just below average. At most, the umps got 2 or 3 pitches wrong per game if they had an average series.

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by bs.uf15bosox9bears23 on Apr 20, 2009 7:15 PM EDT reply actions 0 recs

For each ump, can you find the rectangle that creates the highest percentage of "correct" strike/ball calls...

… where “correct” means matching the ump’s actual call to where the pitch falls relative to the box you give him.

Beyond the Boxscore // Calling BJ Upton lazy is lazy.

by Sky Kalkman on Apr 21, 2009 5:45 PM EDT reply actions 0 recs

I am trying thatt, but what size of box to use.

Right now I am just moving the 90% strike and ball zones around until they have the most correct.

I am thinking of going the other way and moving the box first and then changing it to the 90% value.

It is definitely a trial and error process. It would be nice to with a single query, but I haven’t been able to get one that finds all 4 variable (x and y in the zone and the size in the zone). All this assumes the ump has a perfectly square strike zone.

by Jeff Zimmerman (TucsonRoyal) on Apr 21, 2009 6:27 PM EDT up reply actions 0 recs

Heat maps!

Beyond the Boxscore // Calling BJ Upton lazy is lazy.

by Sky Kalkman on Apr 21, 2009 6:55 PM EDT up reply actions 0 recs

Let me know a good/easy program for them would be great

Reading about heat maps I saw what I might end up doing. Create a matrix of at .1 (ambious) or .2 (lazy) intervals and put the % of balls and strickes in each box.

by Jeff Zimmerman (TucsonRoyal) on Apr 21, 2009 7:41 PM EDT up reply actions 0 recs

I posted a link to this as a FanShot on OTM.

And used some of the data to describe the umpire that was supposed to be behind the plate tonight at Fenway.

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by bs.uf15bosox9bears23 on Apr 21, 2009 8:25 PM EDT reply actions 0 recs

Interesting Work

But their data seems too consistent with each other. No single umpire got more than 85% or less than 80% correct.

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by hubcityraider on May 7, 2009 2:16 PM EDT reply actions 0 recs

Does that imply bad data? Or does it support consistent umpiring?

Beyond the Boxscore // Calling BJ Upton lazy is lazy.

by Sky Kalkman on May 7, 2009 7:00 PM EDT up reply actions 0 recs

I actuall an thinking the 5% is pretty bad in that over a 240 pitch game it is a difference of 12 pitches

The main problem I am finding with the work so far is that it is pretty tough to find and umpire’s personal zone because it seems that most of them have a zone that is not square. I want to look at them with heat maps which requires me to learn R. It is short on my list, but a couple of other projects in front of it.

by Jeff Zimmerman (TucsonRoyal) on May 7, 2009 7:13 PM EDT up reply actions 0 recs

Somebody please help me out here:

I am fascinated by the whole questec and pitch f/x approach to measuring balls/strikes, and what all that can say about the Derek Jeter’s on offense, or the Greg Maddux’s on the mound, or the Eric Gregg’s behind the plate.

What I do not get, however, is how the upper and lower bounds of the zone are defined within pitch f/x data, as opposed to what the actual rule book states and what the umpire is able to adjust per batter (size, stance, position in the batter’s box).

I understand that Questec had an operator who made a manual adjustment to the system when the batter stepped into the box. The implication of that task is that there was a recognition that the upper/lower bounds differ and needed to be taken into consideration.

If pitch f/x makes no actual adjustment per batter (and some “usual and customary” figures are used, such as the 1.5/3.5 used here), how can pitches measured by pitch f/x at the top and bottom edges of the zone be used to study any accuracy of an umpire’s call?

by Stirrups on May 8, 2009 3:04 PM EDT reply actions 0 recs

I actually adjusted all my vertical values by following method

Adjusted pitch height = Measured Pitch Height – (((Batter High Zone + Pitcher Low Zone)/2) – ((3.5 {theroretical high zone] – 1.5[theroretical Low Zone])/2))

For example someone with a zone of 4 to 2 and the ball thrown at 3ft, the ball gets adjsut to:

3 – ( ((4+2)/2) -((3.5+1.5)/2)) = 3 – (3 -2.5) = 3 – .5 = 2.5

So a pitch that is at 3 for 4/2 hitter is 2.5 for the 3.5/1.5 hitter.

by Jeff Zimmerman (TucsonRoyal) on May 8, 2009 3:59 PM EDT up reply actions 0 recs