Automated Strike Zone Baseball
Automated Strike Zone Baseball

In case you missed it, a computer was used recently to call balls and strikes in a minor league baseball game. The PITCHf/x system, created by Sportvision, is in every MLB ballpark and is used on telecasts to show pitch location (and to second guess the plate umpire).  Eric Risberg/AP

Ex-player and screen


The game was between the host San Rafael Pacificas and the Vallejo Admirals of the Pacific Association. The pitches were actually called by former MLB player Eric Byrnes over the PA system while watching a computer screen.

Eric Risberg/AP


The PITCHf/x system uses three cameras to triangulate each pitch from the pitcher’s hand to just in front of home plate measuring speed, trajectory and location. Since 2008, PITCHf/x has been operational in every MLB ballpark. It has captured a wealth of data allowing countless analysis of pitchers and umpires. Here’s a short story about umpires’ tendencies.

By Etan Green
Consider a forgotten game in April 2010 between the Cleveland Indians and the Chicago White Sox. The White Sox were up a run with two outs in the eighth. Their set-up man, Matt Thornton, was on the mound, protecting a lead with a runner on first and the right-handed Jhonny Peralta at bat. Ahead in the count with one ball and two strikes, Thornton froze Peralta with a slider on the outside half of the plate, a couple inches below the belt. For a pitch like that, the umpire, Bruce Dreckman, would normally call a strike — 80 percent of the time, the data shows. But in two-strike counts like Peralta’s, he calls a strike less than half the time.


The PITCHf/x data is readily available and several sites compile and report the data. Here’s Johnny Danks pitch (%) breakdown by month for 2015.

Danks-2015 Pitches

In 2007, Johnny didn’t have a cutter so he relied on the four-seam fastball.

Danks-2007 Pitches

And, the day after White Sox rookie Carlos Rodon threw his best game, I found the chart below that identified every pitch he threw! This was one of twelve charts that detailed Carlos’ performance.

BrooksBaseball Chart

McClelland Calls 20090704

And, here’s a chart detailing every call made by umpire Tim McClelland during a White Sox game on July 4, 2009 for left-handed batters. The chart is from the umpire’s point of view. The extension on the outside portion of the plate represents the normal strike zone that MLB umpires use for left-handed batters. Several articles that I’ve read attribute the recent lower batting averages and increased strikeouts to the expanded strike zone since the advent of PITCHf/x. The strike zone itself has not expanded, but the strike zone being called by umpires has grown because they are now evaluated using PITCHf/x. More strikes at the bottom of the zone are now being called.

For more info (from PITCHF/X) than you’d ever want to see, visit http://www.brooksbaseball.net/dashboard.php


Rule 2.00: The Strike Zone The STRIKE ZONE is that area over home plate the upper limit of which is a horizontal line at the midpoint between the top of the shoulders and the top of the uniform pants, and the lower level is a line at the hollow beneath the kneecap. The Strike Zone shall be determined from the batter’s stance as the batter is prepared to swing at a pitched ball. (2015 version)

Strike Zone 2015———-

Rule 2.00 above and the chart to the left are from the official MLB Rulebook. It’s about 100 pages of stimulating reading.

The strike zone hasn’t changed in recent years,  although I noticed that the 2015 graphic is the first time the batter has worn a batting helmet.

Baseball Rulebook



On Saturday, in the White Sox 1-run loss to the Royals, the last out was a called strike three on Sox batter Jose Abreu. The pitch was obviously a ball and Hawk Harrelson was still pointing that out during the Sox telecast four days later. Of course, this works both ways. Here’s a picture I took off of my TV of the last pitch by Sox closer Ronald Belisario in a game last season. The pitch was clearly a ball, but was called strike three for the last out and a save for Belisario.

Save on a BallMy recollection is that Hawk did not mention the umpire’s error in this instance.

Although, in defense of Hawk, he sometimes says, “We got a break there” when the call goes in favor of the Sox.


Hawk does not envision the day when a computer calls balls and strikes. His position is that as long as the umpire is consistent and calls pitches badly for both teams, everything is OK. How is this a good thing? I’m a little surprised by Hawk’s resistance to embrace the latest technology because he constantly talks about how great his iPad is and how he can track every game in real time.

I long for the day when pitches are called more accurately. Perhaps the plate umpire could have a small red light inside his mask that would instantly turn on for a strike so he could still make the call in a timely basis when necessary. E.g. a runner breaks for second on a 3-2 pitch with less than to outs — does the catcher need to make the throw? Of course, the home plate umpire would still call check swings (sometimes with help as they do now), hit batsmen, fair/foul balls up to 1st & 3rd base, foul tips, plays at the plate, batter or catcher’s interference, etc. And, he could still clean off home plate.  Does anyone remember when Bill Veeck installed an air hose that popped up in the middle of the plate to blow off the dirt?

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2 Responses to PITCHf/x

  1. Chuck says:

    Hope BArb getting better. We are at the game but Terry is in her Cubs shirt. I am being nice. Chuck

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