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December 5, 2013
Measuring Pitching with TrackMan
The Secrets of Fastball Spin
Zach Day was drafted by the Yankees in the fifth round of the 1996 draft and pitched for three MLB teams from 2002 to 2006. He had stints with the Expos, Nationals, and Rockies, compiling a 21-27 record with a 4.66 ERA. Zach has been with TrackMan Baseball since 2008 and has played a critical role in introducing the technology to pitching coaches, scouts, and on-field personnel. This is the first in a series of articles in which he’ll discuss what TrackMan’s measurements reveal about pitching.
What’s a good fastball spin? As evidenced by the chart below, the spin put on a fastball directly correlates to ground ball rate, fly ball rate, and swings-and-misses. (As for whether high or low spin on a fastball is better—that’s a topic for a different day.) Knowing your spin helps you better understand what type of pitcher you are at present.
The “sneaky” description comes immediately to mind when I think about my former teammate Chad Cordero, and not because of the flat-billed cap hiding his eyes. Hitters would take called third strikes at the knees from Cordero because they were expecting the ball to drop out of the strike zone. His deceptive spin caused hitters to take, swing-and-miss, and foul off what seemed to be an unusual number of pitches. Unfortunately, we don’t have Chad’s spin rate from his 2005 season, when he had 47 saves and a 0.969 WHIP, but Boston’s Koji Uehara is a great contemporary example of a pitcher with a high-spin heater.
A ball thrown with true backspin that spins at a high rate will work against gravity, causing it to sink less quickly than a ball with lower spin. As a result, hitters’ eyes are deceived, because the ball doesn’t sink as much as they expect it to. No one can defy gravity completely and throw a rising fastball, but pitchers can work with and against gravity as a form of deception.
Want to test this out? Set up a pitching machine to throw an 80 MPH fastball with 3000 RPMs and see how hard it is to hit. Don’t be surprised if you find yourself swinging through and fouling off pitches. You won’t see this offering in actual games—no current pitcher throws a fastball with 3000 RPMs.
Two pitchers who throw 95 MPH can have drastically different spin rates. One may have a fastball with a spin of 2500 RPMs, while the other gets 1800 RPMs. Lower-spin fastballs work against gravity less, causing them to sink at a higher rate than high-spin fastballs.
Have you ever played catch with someone who throws a hard and heavy ball? A low-spin fastball will sink more than you expect and hit your glove closer to the palm of your hand, while a high-spin or even average-spin fastball will more likely hit your glove in the web.
You can lower fastball spin just by changing your grip. A two-seam fastball will have less spin than a four-seam fastball. The same would be true of throwing with one seam or even no seams, which is sometimes called a slip pitch. By splitting your fingers and throwing a fastball, you are effectively taking spin off the pitch and causing it to drop at a higher rate than normal for that velocity.
This could at least partially explain why using spit or Vaseline on a ball can be an advantage. Vaseline would take spin off a fastball, causing it to drop.
It’s Good to Be Different
Even though spin has been discussed in baseball forever, it’s only recently that we’ve gained the ability to measure it accurately. Knowing what we’ve learned about the effects of fastball spin—Westbrook creates more sink by taking spin off his fastball, while Uehara’s high spin causes his fastball to sink less—we can tell whether a pitcher is a ground ball or fly ball guy, and to what degree, without seeing him throw a pitch. Based solely on Trackman data collected at a Perfect Game event, Howe (TX) High School senior Garrett Fulenchek is an extreme sinkerball pitcher right now. You can see some of the high-spin fastball pitchers from the recently concluded Arizona Fall League below.