Searching for Buchholz's spitball

Using PitchFX data to examine if the Red Sox pitcher is throwing a spitball

Originally Published: May 6, 2013
By Eno Sarris | FanGraphs
David Ross, Clay BuchholzJohn E. Sokolowski/USA TODAY SportsClay Buchholz was accused of throwing a spitball against the Toronto Blue Jays.

The accusations are on the table. As Gordon Edes reported on ESPN Boston, Jack Morris said he thinks that Clay Buchholz was throwing a spitter in his start against the Toronto Blue Jays last week, and we know the baseball world will be watching Buchholz closely when he toes the rubber on Monday night against the Minnesota Twins.

It's not easy to test these accusations, despite the fact that every moment of the start was recorded on video and baseball creates more data than any sport. Those who have looked closely at the Boston Red Sox pitcher's forearm have not decided conclusively whether it's just sweat and rosin or if there is definitely something else going on there.

[+] EnlargeBuchholz Pitch FX 2013
FanGraphsBuchholz's last start was not out of the ordinary in terms of movements.

So let's avoid the screen captures of sweaty forearms and try to find the spitball in the numbers. PITCHf/x gives us data for the horizontal and vertical movement of every pitch. We should be able to find the outlier in the data … if it exists.

The quest for a spitball is just the quest to find a pitch that looks different. A pitch that doesn't fit in. A fastball that moves too much, since that's what caught Morris' eye.

To the right are all the fastballs from Buchholz's May first start against the Blue Jays, plotted by X and Y movement.


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