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April 23, 2009 12:30 pm

Checking the Numbers: Inside Pitch-f/x


Eric Seidman

Dissecting a day at the office for the Mets' Johan Santana.

Due to local blackout rules and the lack of a land-line phone capable of proving that my Penn State University residence was not in Philadelphia, I relied on MLB Gameday instead of MLB TV for a good chunk of the 2007 season. The application had been around for a while, but I soon noticed strange terminology and new data accompanying each pitch. Why are there two velocity readings? What does 13" of pFX mean? And what the heck is BRK? A little research soon made sense of the information, and within a few months I became hooked on the data set known as Pitch-f/x. Fast-forward two years, and Pitch-f/x continues to evolve, revolutionizing baseball research in the process. Unfortunately, with updates to system configurations and the amount of information offered, too many readers and baseball fans experience confused reactions similar to mine when they first encounter the data. In an attempt to quash this issue, it seemed prudent to explain some of the more commonly used numbers, discussing what they mean as well as how they should be used. Instead of merely defining terms, the system will be explored in action, with periodic discussions of its inner workings, much as Dan Fox did back in May 2007.

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June 9, 2008 12:00 am

Ballad of the Fatigued


Eric Seidman

How do starters who throw particularly high pitch-count initial innings perform subsequently?

Delivering to the dish with a 2-2 count, Wandy Rodriguez hit the outside corner with a 91 mph fastball with which Edgar Renteria could do nothing but whiff. This heater happened to be the 55th pitch that Rodriguez threw in the inning on August 1, 2007. While the pitch brought the inning to a close, it simultaneously placed Rodriguez atop a list of the pitchers who had thrown the most pitches in a single inning. Compiled by Retrosheet's David Smith and posted on the Inside the Book blog, the list is composed of the pitchers with the most pitches thrown in an inning from 2004-2007.

I decided to examine the Pitch F/X for Wandy's game. Analyzing the velocity and movement of Rodriguez's fastball, I was surprised to find that his fastball sustained its velocity and "bite" as he went deeper into the inning. However, during the rest of the game things changed a bit. In the second inning, his velocity lost three miles per hour, but his movement increased. It has been theorized before that some pitchers may throw with more movement when they tire due to a dropping of their arm angle; perhaps this happened here, as Wandy lost velocity but threw with more movement.

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Some prospects are up in The Show, some are just up, and some really aren't. Who among our top 100 are headed in which direction?

1. Alex Gordon, 3B, Royals
Eligible Next Year? No
Stock Movement Since Ranking: Unchanged

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Is it there, or isn't it? Dan dives into Dice-K's data to find out.

"Hmm. How should I answer that question? I knew this question was coming today. And I was preparing some optional answers for this particular question. Should I say, 'I have that ball?' Or I could say, 'Which particular ball are you referring to?' Or 'Which ball are you calling a gyroball?' Overall, if I have the chance, I will pitch that ball."
--Red Sox pitcher Daisuke Matsuzaka, answering a reporter's question during his first press conference after arriving in Fort Myers for spring training.

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Popping the hood on King Felix as a demonstration of what's possible with PITCHf/x data

"Hell, yeah, I want to throw that pitch. They don't let me, though. They tell me I'm too young, that it's bad for my elbow. I told them I want to throw it."
--Felix Hernandez talking about his slider before the 2006 season

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March 16, 2006 12:00 am

Future Shock: Taking a Step Back, Part Three


Kevin Goldstein

Kevin finishes his scouting primer with a look at how pitchers are evaluated.

The Scouting Scale Returns:

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