2008 pitch f/x data

by Adam J. Morris on Jun 2, 2008 2:01 PM CDT

There's a blog a BoSox fan is doing, that concentrates on pitch f/x data.

Today, he has a post up that aggregates all the pitches by velocity, gives the results from each group, and looks at the BABIP data for each group.

Pretty cool stuff...check it out...

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Yawn.

by brettgardner on Jun 2, 2008 2:35 PM CDT reply actions

Your opinion has been duly noted

by Adam J. Morris on Jun 2, 2008 3:15 PM CDT up reply actions

Hey

I told you my bit.

by brettgardner on Jun 2, 2008 3:22 PM CDT up reply actions

Okay, this still kinda confuses me.

That post doesn’t show it, but for anyone who’s checked pitch data on GameDay: it lists pitch speed, break (in inches), pFX (in inches?), and result (strike, foul, ball, etc.).

I couldn’t draw a correlation to either the speed difference (GameDay shows out-of-hand velocity as well as across-the-plate velocity), a combination of break and sideways movement, or anything else shown on the display. Does anyone know what this pFX number should represent?

by jwiscarson on Jun 2, 2008 3:07 PM CDT reply actions

I've been getting Jeff Sullivan to help me with this

Basically, the pfx_x reflects the horizontal break, the pfx_z reflects the vertical break. With x, the closer to 0, the less break. A big positive, or a big negative, number means more break. With z, the lower the number, the more break. Fastballs generally will be at 10-12, with curves being negative.

by Adam J. Morris on Jun 2, 2008 3:15 PM CDT up reply actions

Thanks, Adam.

This confused me because GameDay doesn’t separate out the axes (although I suppose their “break” could be x and pFX could be z). The numerical switching info helps a lot as well.

Leave it to Major League Baseball to get something as simple as plotting points on a two dimensional plane wrong.

by jwiscarson on Jun 3, 2008 1:33 AM CDT up reply actions

To clarify my last sentence...

I was referring to “less break” approaching zero on the x and approaching some undetermined positive number on the z. As a computer scientist, this bothers me greatly.

by jwiscarson on Jun 3, 2008 1:36 AM CDT up reply actions

In this case, though...

The data he is provided is simply velocity, not break.

by Adam J. Morris on Jun 2, 2008 3:15 PM CDT up reply actions

By the way, MLB maintains a database of all gameday data

In XML format. There is whole lot more information in there, like velocity and acceleration in x/y/z components, release point, release velocity, pfx_z and pfx_z, location and etc for every pitch. The actual gameday itself only gives break, velocity, and pFx in inches. Adam has explained what they are.

by Telegraph on Jun 2, 2008 3:36 PM CDT up reply actions