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An Olympic Yardstick – Pitch Rotations Follow-Up

tanya harding australia spin rate pitch movement olympian rotation

In the last issue of the SE Insider, in the article titled “An Olympic Yardstick – Pitch Rotations”, I listed some spin numbers. These numbers were taken using the RevFire.

While this device is no longer available, the numbers do stand up to the popular Rapsodo pitching monitor, so let’s see how.

RevFire and Rapsodo measure the same thing – how many times a ball spins on its way to the plate. They just list the results differently.

The spin numbers in the Olympic Yardstick measured Tanya Harding, 4-time Softball Olympian for Team Australia, using the RevFire spin rates of Rotations Per Second (RPS):

Pitch Average Top
Fastball 20.8 22.7
Riseball 25.2 27
Dropball 18.8 19.7
Curveball 25.1 25.8
Change Up 13.8 14.1

To see how significant these Spin Rates are, let’s compare these numbers to the Average and Top spin rates of college pitchers:

Pitch Tanya Avg. College Avg. Tanya Top College Top
Fastball 20.8 19.2 22.7 23.1
Riseball 25.2 21.7 27 26.6
Dropball 18.8 20.9 19.7 25.7
Curveball 25.1 21.2 25.8 26.6
Change Up 13.8 no numbers 14.1 no numbers

Rapsodo uses Rotations Per Minute (RPM) to measure spin rates:

rapsodo rotations per minute pitch spin movement

So let’s look at the Riseball from a college pitcher:

  • RevFire lists it as 21.7 Rotations Per Second (RPS)
  • Rapsodo lists it as 1337 Rotations Per Minute (RPM)

To make these two seemingly different numbers speak the same language, it’s a matter of math:

  • RevFire: 21.7 RPS x 60 seconds in a minute = 1,302 RPM (pretty close to 1337 RPM from Rapsodo)
  • Rapsodo: 1,337 RPM / 60 seconds in a minute = 22.28 RPS (pretty close to 21.7 RPS from RevFire)

Bottom line, whenever you compare things that are measured from different devices or using different methods, be sure to compare apples to apples.

Oh, and it also shows that both of these devices come up with pretty much the same thing.

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