A Summer of Spin Rates

As some of you may know, this summer I’m working for the Oakland Athletics as a Trackman Operator — which is basically a fancy way of saying that I’m “keeping the book” plus a few extra things, for the A’s short-season single A team in Burlington, VT. Some of those “few extra things” are spin rates, extension, exit velocity, launch angle, and some (23) more.

Now, I don’t totally understand what all of these metrics mean and what their purpose is — so in this article I hope to give you all a basic understanding of what they are but also help educate myself as well.

To break down what the Trackman system (think of a fancy radar gun) measures, I’ll first take look at the pitching-side. This article will just be about pitchers. Stay tuned for an explanation of the data collected from hitters. Four of the more common types of data that the system collects from pitchers are pitch velocity, spin rate, extension, and tilt.

Pitch Velocity

The is the one that you are all probably familiar with — the speed of the ball coming out of the pitcher’s hand. People usually associate velocity with fastballs. The hardest fastball ever recorded in MLB was Aroldis Chapman’s 106 mph pitch in 2010. The average fastball velocity so far in 2016 is 92.1 MPH — up from 90.5 in 2006.

Spin Rate

Spin rate is the speed of the ball’s rotation (in RPMs) once it leaves the pitcher’s hand. Spin rates on fastballs help discover if a pitcher allows more ground balls or fly balls. The lower the spin rate (MLB average is 2200 RPM), the more likely a batted ball will be a ground ball. A hard fastball with a low spin rate tends to have sinking action. A higher spin rates results in more fly balls. Spin rates also affect the likelihood of a swing-and-miss. Swing-and-misses happen more when the spin rate is above the league-average, and vice versa.

Some fastballs are described as “sneaky” — meaning that the ball gets to that batter faster than the batter first expects. Sneaky fastballs usually have below-average velocities but above-average spin rates. Think of Koji Uehara — a pitcher that doesn’t throw hard but gets a lot of swings and misses.

Matt Bush (yes, the guy drafted #1 overall in 2004 as a shortstop and was considered a huge bust until this year), has the highest average fastball spin rate in 2016 at 2,544 RPM.

While I won’t get into too much detail about spin rates of other pitches, curveballs and sliders tend to spin faster than fastballs and changeups tend to spin slower.


Extension is the distance (measured in feet and inches) from the pitching rubber to the point where the ball is released from. The greater the extension the closer the pitcher’s hand is to home plate when he releases the ball. Extension can tell us about perceived velocity, which is different than actually velocity. Think of two pitchers who throw an identical speed. Except one pitcher releases the ball 54 feet from home plate and the other releases from 53 feet. The radar gun both shows they throw 95 mph, except the batter is at a disadvantage facing the pitcher who releases the ball 53 feet away from home plate. Why? He has less time to react. The ball gets to him quicker because the ball is released closer to him. So the 95mph pitch from 53 feet may appear 97mph to the batter.

Carter Capps and his hop-off-the-mound delivery has the largest average extension at 8 feet 4 inches. His average fastball velocity of 98.1 mph has a 101.7 mph perceived velocity. On the other extreme, Joel Peralta has a 4 foot 11 inch extension. Batters perceive his 90.2 mph fastball at a pedestrian 87.6 mph.


Tilt is the direction the ball is spinning once it leaves the pitcher’s hand.

That’s all I got for tilt. I can’t find a more detailed explanation or even a short blurb on why it’s important.


Read about the hitting measurements (part 2) here.








Posted by Jeb

From the great "vacationland" state of Maine. Former D3 baseball player on an underachieving team. Prior: TrackMan with A's. Current: Check Down Sports. Soon: Video with Reds. All-time facial hair lover.

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