Comparing the Rapsodo Baseball Device to Other Pitch Trackers

Rapsodo wants to bring pitch tracking to the masses.

Rapsodo wants to bring pitch tracking to the masses.

Our fascination with tracking pitches began with measuring their velocity, over 100 years ago. The first attempt, in 1912, involved a chronograph, a shooting range, Nap Rucker and Walter Johnson. This display of speed involved Johnson and Rucker throwing into a 15-foot tunnel that was encased by copper wires and ended with a steel plate, measuring the velocity of the pitch at the end of its trajectory. Johnson hit 83 mph and Rucker 77 mph.

By 1914, humans had moved on to more sophisticated means of measuring velocity, like racing a fastball against a motorcycle. Pendulums, stop watches, analyzing film, more advanced military-chronographs, and more motorcycles were all used during the first three quarters of the 20th century to measure pitch speed. It wasn’t until 1975 that MLB adopted Doppler radar, and it has grown ever since. At every stadium, from the minors up, pitch velocity is available to the crowd, usually cushioned between local ads for furniture and pizza. Measuring velocity is great — it allows us to believe we could pitch faster than Jered Weaver — but, with the advance of technology at the turn of the century, spin is becoming the new velocity.

It began with Sportvision’s PITCHf/x, developed with MLB in 2006. Now installed in every major league stadium, PITCHf/x uses three tracking cameras and a central tracking system to calculate movement caused by the Magnus force, measuring velocity, movement, release point, pitch location and spin. PITCHf/x was baseball’s first venture into these more advanced pitching measures. These statistics became more available to fans through MLBAM and Dan Brooks’ Brooks Baseball.

After Sportvision’s success, TrackMan, initially a Danish golf technology company, jumped into baseball in 2008. Using military-grade Doppler radar, TrackMan measures the location, spin, break, velocity and trajectory of pitches. The system involves a single radar positioned behind home plate, now in every MLB stadium, providing data for Statcast.


The success of these two pitch tracking behemoths has paved the way for other companies to delve into measuring spin. Rapsodo, FlightScope and RevFire (now discontinued) have all created devices to track pitch metrics. FlightScope also includes hitting. There is also a product from PitchGrader designed to analyze the pitch data obtained from a Doppler radar. RevFire was a handheld monitor that could provide velocity and spin rate data after each pitch, providing instant feedback. It does seem like RevFire is coming back with a new product, the RevFire 2, but no date for its release is available online.

FlightScope is another golf analytics company that began in missile defense tracking in South Africa. It moved on to cricket in 1995, then tennis, and now baseball with the FlightScope Strike. Released this past August, the Strike uses thecompany’s signature multi-frequency 3D radar technology to provide data on horizontal and vertical break, spin, movement and trajectory, on top of velocity and extension. It also provides hitting metrics like exit velocity, launch angle and distance.

We spoke with FlightScope’s Baseball Application Specialist David Mayberry to get more information about the device. We spent a lot of time discussing how FlightScope differs from other devices on the market. Mayberry’s main focus was on TrackMan, an idea that began in a FlightScope conference room and is now one of its direct competitors. Mayberry said the Strike has performed more accurately than TrackMan indoors, despite using virtually the same technology. Unlike TrackMan, clients of FlightScope own their data and get a spreadsheet with the numbers after a session. Another advantage provided by the Strike over Trackman is its portability.

Mayberry said FlightScope has partnered with USSSA, worked with 12 major league teams, and is working with a top team in Japan. FlightScope has done extensive validation with the Dodgers and Astros in their instructional league and will be providing data to teams in spring training. FlightScope also works with bat manufacturers like Easton and DeMarini so they can advertise accurate features about their bats.

Mayberry seemed most excited about the Strike’s revolutions statistic. This provides the actual number of revolutions a pitch undergoes during its trajectory instead of revolutions per minute. So for a major league average 92 mph fastball, the number of revolutions would be roughly 15 instead of the traditional 2200 rpm. Mayberry believes this provides the pitcher with a more consumable and easier to comprehend number than rpms. He emphasized that FlightScope’s niche is in player development, as seen with its extensive work in youth baseball.

The FlightScope Strike may not be a direct competitor with Rapsodo. Along with pitch metrics, the Strike provides batted ball data and defensive data, which Rapsodo does not set out to do. These added features come with a larger price tag — a one-time $18,000 purchase. Due to the cost and features offered by FlightScope, it competes more directly with TrackMan.

This leads us to Rapsodo.

This past year, Rapsodo announced a new, portable, pitch tracking device, titled simply as Rapsodo Baseball. Historically it has been a golf analytics company, like Trackman and FlightScope, this was Rapsodo’s venture into the world of baseball. The device aims to make major league-level pitch data available to high school and college teams.

Rapsodo hopes to improve the pitcher training with easy-to-comprehend and useful data so that pitchers have a better understanding of what they are throwing. The device involves a single monitor on a tripod that can measure velocity, total spin rate, true spin, spin efficiency, tilt axis and break, using a combination of camera and radar technology to measure the pitch data. The device measures pitch metrics in a similar vein as PITCHf/x, but with a more affordable price. The Rapsodo unit will run you about $3,000, compared to the many more thousands of dollars for a PITCHf/x, TrackMan or FlightScope setup.

Rapsodo is already gaining traction in the world of baseball, with former Red Sox reliever Craig Breslow using the device to train. Breslow, a molecular biophysics and biochemistry major from Yale, wants to use the Rapsodo monitor to receive real time data about his pitches and improve his pitching, which has been a disappointment since the 2013 season.

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We (the Baseball Analysis at Tufts club) received a demo unit this fall and set out to test the usability and performance of the device. The unit comes with the monitor, a tripod, two poles and a cage for the monitor, and the setup was very simple. To get the unit ready for testing, you simply plant the tripod in the ground, screw in the two additional poles to add height, then screw on the cage and place the monitor on the mount plate within the cage.

The unit is set six feet behind home plate, or 66 feet and six inches in front of the rubber. This distance allows the ball to travel through the zone where the monitor can track the pitch. We had initial concerns that a wild pitch could break the unit and we would be liable for $3,000, but Seth Daniels, director of sales, reassured us that the tripod and monitor cage are designed to withstand up to a 100 mph pitch. Since Aroldis Chapman never returned our emails to measure his pitches, we were fine.

Dan pitching his knuckleball to Stan. Green light indicates the device is ready to measure.

Dan pitching his knuckleball to Stan. Green light indicates the device is ready to measure.

When the device is set up, it can connect to your laptop/tablet with the downloaded software (currently available only on Windows devices) through either wifi or the provided USB cable. Both connections worked, but due to the nature of the laptop we used (read: very old), we used the USB cable. Once the link between the monitor and laptop/tablet is initiated, you can connect to the wifi network established by the device.

When the device is ready to start, the light on the back of the monitor will turn green. To begin testing, the monitor must be centered and at a 20 degree angle to the ground. The calibration screen in the app makes this process quick and easy. The view needed is just in front of the pitcher and splits the mound in half. When these conditions are satisfied, you tighten the screws on the mount plate to hold the monitor in place and start measuring. The total setup process took no more than five minutes.

The device was tested outside as well as indoors. Due to the fact that we tested it late in the New England fall, we were not able to get too much data outside. However, the pitches we did record showed the trends we would have expected from the pitchers who threw, with the best Tufts pitchers throwing harder and with more efficient spin and better break than the more average pitchers.

Most of our testing was indoors with Brandon, Stan, Dave and Dan, pitchers from Tufts’ club baseball team. Brandon, Dave, and Dan played for the varsity team in the past. All pitchers threw a mix of fastballs, change-ups and breaking pitches. However, to avoid putting too much strain on our volunteers’ arms, the majority of the pitches thrown were fastballs and change-ups.

Rapsodo app readout following a curveball (incorrectly marked FB) from Brandon.

Rapsodo app readout following a curveball (incorrectly marked FB) from Brandon.

The metrics recorded were total spin, true spin, spin efficiency, tilt axis, velocity and break. Total spin is a measure of topspin, backspin, sidespin and rifle spin. Rifle spin doesn’t correlate to pitch movement so true spin is total spin minus rifle spin. Pitch efficiency is a measure of the ratio of true spin to total spin, effectively a measure of useful spin. The other measures recorded with Rapsodo should be pretty self-explanatory.

Let’s break out some graphs to show you what we found.

Overhead view of Dave’s curveball. Dashed line is the pitch without break and the solid line is the trajectory of the actual pitch.

Overhead view of Dave’s curveball. Dashed line is the pitch without break and the solid line is the trajectory of the actual pitch.

Horizontal and vertical break of Dan’s knuckleball.

Horizontal and vertical break of Dan’s knuckleball.

We initially set out to compare the Rapsodo unit with PITCHf/x, a well-established pitch tracker. We had Brandon and Stan pitch in front of the Sportvision system at the SmartKage headquarters in Tyngsboro, Mass., as well as in front of the Rapsodo device. Unfortunately, due to the nature of the layout at the SmartKage facility, we were not able to directly compare pitches for both systems. Also, when we later spoke to Daniels, he noted that the key difference between Rapsodo and PITCHf/x is the way they measure pitch break and spin, making a direct comparison essentially useless.

Daniels further to clarified what Rapsodo does differently from Sportvision. Daniels told us that Rapsodo follows the approach recommended by Dr. Alan Nathan, which includes removing drag and gravity from the measurements, giving more accurate spin and break numbers but different from what PITCHf/x would produce. Daniels said that Rapsodo’s method has received approval from an undisclosed major league team, along with many others in the industry, so the firm trusts it is on the right path. Due to the gravity/drag aspect, Rapsodo’s measurements of spin and break will be inherently different than other pitch trackers.

Since we were unable to validate the data by comparing it to PITCHf/x, we looked at the consistency of our pitch data over the course of two bullpen sessions (BP 1 vs. BP 2), in particular with Brandon’s pitches. While tracking pitches outside, we had compared velocity from Rapsodo with values from a Stalker radar gun and found that the numbers were comparable. While velocity is an important measure, the essence of Rapsodo is in spin and break.

Spin efficiency differences between Dave and Stan, demonstrating what we would expect. Dave, more of a true pitcher than Stan, had much better spin efficiency on both his fastball and change-up.

Spin efficiency differences between Dave and Stan, demonstrating what we would expect. Dave, more of a true pitcher than Stan, had much better spin efficiency on both his fastball and change-up.

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The sizable variation in the data can largely be attributed to small sample size. However, most of the metrics measured remained fairly constant across the two bullpen sessions, with fastball true spin dropping off by around 100 rpm in the second bullpen session. The change-up data remained more constant than the fastball data. There were not enough curveballs or sliders thrown to offer reliable analysis, but the data are available upon request.

This is not the be all end all analysis of Rapsodo’s accuracy, but we were happy with the results and how they held up over time. The pitchers we worked with found the data helpful, giving them a good idea of what they were throwing and how they could improve from here. People with better backgrounds than us in coaching pitchers will be able to use the data to help their pitchers improve.

The big advantages of Rapsodo over other pitch measuring devices include the price, usability and portability. The unit comes with a regular-sized duffle bag which nicely fits the tripod, cage and monitor. In contrast to PITCHf/x, as long as you have 66 feet and six inches, the device can be setup anywhere. There’s no special installation required. A tall child could literally do it.

Getting it started to measure pitches is also simple. When we visited the SmartKage facility to use the PITCHf/x system, it took at least 15 minutes to get the system going and required a large computer, not to mention the three pre-installed cameras and central tracking device.

It is tough to directly compare Rapsodo with the FlightScope Strike. The Strike provides a lot of value in its hitting metrics, allowing for pitcher/hitter match-up analysis. It also tracks the pitch trajectory and gives you a visualization of the pitch and batted ball overlaid on a field graphic, which Rapsodo can do only for the pitch.

Both devices measure the same pitching metrics, although Rapsodo has the added benefit of spin efficiency. Rapsodo and the Strike are also portable and provide data right to a tablet. The setup for each device is very similar. Both come with a tripod on top of which the pitch monitor is placed and both create their own wifi hotspot to connect to.

However, one of the advantages the Strike holds over Rapsodo in the pitching sphere is that it only uses 3D Doppler radar. Due to the combination of camera and radar, Rapsodo is unable to measure through screens, which can obstruct the view of the camera and make data unusable, a problem we ran into in Tyngsboro. The Strike can measure through a net, which makes it more convenient/safer for the device if placed behind a catcher. Also, the Strike does not need to be set up anywhere specifically. Rapsodo requires installation six feet behind home plate, which is not always possible. This aspect of the Strike may prompt teams to look into using the device for their bullpen, where space is limited.

In terms of pitching data, device setup, and features, Rapsodo and FlightScope’s Strike are pretty similar. The Strike does provide additional value in hitting data, which Rapsodo did not set out to do.

The biggest draw for teams deciding which device to purchase is the price. Rapsodo is roughly 10 times cheaper than PITCHf/x and Trackman and six times cheaper than the Strike. In our (D-III) experience, few teams would be willing or able to drop $18,000-$30,000 for a device like the ones discussed. Rapsodo provides an excellent product at a price more reasonable for high school and college programs. If a team is looking for a device to measure solely pitching metrics, for $3,000 Rapsodo is tough to beat.

In conclusion, we found the Rapsodo device is best used during bullpen sessions, either outside or inside. This way, the monitor can get a clear view of the path of the pitch without batter or swing interference. The biggest issue we found with the device was the inability to export data. When creating these graphs and averaging our pitchers’ data, we manually recorded the data into an Excel spreadsheet. However, this issue is relatively minor considering what this device is able to do. One of the aspects we were most impressed by was the battery life of the monitor. It was charged fully before using it for the first time and then a month later, after roughly 12 hours of use, the battery was at 80 percent.

One thing that stood out when testing the device was how much the players enjoyed it. When we arrived at the first session with the team, no one paid much attention to us. We set up behind the plate and a L-screen and went about our business. A few members of the team who came by between batters to check out the data we were getting. After the first inning of the scrimmage we had several additional people behind the plate with us, wanting to know how fast, with how much break, and with how many rpms the pitcher was throwing.

As the scrimmage went on, more and more guys ended up behind the plate with us, eagerly waiting on velocity, spin data and whether the pitch was actually in the strike zone. By the time Julia’s laptop died, we had about 15 people with us making bets on how fast the next pitcher was going to throw.

That’s one understated aspect of the Rapsodo device: it’s fun. It provides real time data so you can challenge yourself and others to hit certain benchmarks (and it provides an excellent opportunity for teammates to chirp each other about their numbers). Rapsodo has developed a reliable and precise device to measure pitch spin, along with other measures, at an affordable cost.

References & Resources

Max Goder-Reiser and Julia Prusaczyk are students at Tufts University and are members of the Baseball Analysis at Tufts club. Max is Vice President of the club, and Julia has written for Beyond The Box Score. Follow them on Twitter @maxgoderr and @JulPrusac.
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Alan Nathan
7 years ago

Good summary. One minor point: You said ” true spin is total spin minus rifle spin”. Actually, true_spin = sqrt(total_spin^2-rifle_spin^2).

Also, Rapsodo does not measure “movement” directly but infers it from a model relating true_spin to movement. It does measure directly both the total_spin and the spin_axis. Combining these two things allows them to determine separately the true_spin (i.e., the spin leading to movement) and the rifle_spin. By contrast, PITCHf/x does just the opposite: it measures movement more or less directly (from the trajectory) but only infers the true_spin from a model. The rifle_spin is not determined. Finally, Trackman determines the total_spin and the movement directly. With the use of a model, these two things can be used to separately determine the true_spin and rifle_spin.

Rapsodo should agree with Trackman on the total spin. Also, PITCHf/x (when properly analyzed) should agree with Trackman on the movement (both come from a measurement of the trajectory). But it is not possible to compare Rapsodo movement with either Trackman or PITCHf/x. Nor is it possible to compare Rapsodo true_spin with either Trackman or PITCHf/x.

One final note: Rapsodo has recently come out with a batted ball unit that measures exit speed, launch angles, spin, and spin axis. I have not seen it in action but hope to very soon.

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