Since 2008, velocity data has been tracked by PITCHf/x, which is camera-based, and set velocity to be measured 50 feet from home plate. MLB is replacing PITCHf/x with Statcast this season, which makes the measurement a little different. Statcast uses a Trackman radar system to measure velocity rather than a camera, and instead of measuring velocity at 50 feet from home plate, Statcast uses the maximum velocity of the pitch logged by Trackman’s radar. This ends up being directly out of the pitcher’s hand, since the ball slowly loses velocity as it hits air resistance during its path to home. The difference is that velocity is being logged a little further from home plate than in past seasons, since most pitchers average around 6 feet of extension off the mound, which is 60 feet, six inches away from home plate.
The result is that the velocity numbers are higher with velocity logs that use the new system, including Gameday. Andrew Perpetua of xStats.org did some testing and found the difference in fastball velocity to be about .36 mph higher league wide with the new measurement. Of note, this does not appear to affect Brooks Baseball velocity measurements, who will continue measuring velocity at 55 feet from home.
Here is a table of Mets pitchers and their average fastball velocities from last season, with a comparison between the two systems.
|Noah Syndergaard||97.9 mph||98.2 mph||+0.3 mph|
|Matt Harvey||94.4 mph||95.1 mph||+0.7 mph|
|Jacob deGrom||93.4 mph||93.6 mph||+0.2 mph|
|Steven Matz||93.6 mph||93.9 mph||+0.3 mph|
|Jeurys Familia||96.0 mph||96.4 mph||+0.4 mph|
|Robert Gsellman||93.6 mph||94.0 mph||+0.4 mph|
|Seth Lugo||92.5 mph||92.9 mph||+0.4 mph|
|Addison Reed||92.4 mph||92.8 mph||+0.4 mph|
|Hansel Robles||95.0 mph||95.5 mph||+0.5 mph|
|Rafael Montero||92.8 mph||93.2 mph||+0.4 mph|
|Josh Smoker||95.4 mph||95.7 mph||+0.3 mph|
|Jerry Blevins||89.2 mph||89.4 mph||+0.2 mph|
Every Mets pitcher is gaining some velocity to one degree or another with Statcast, ranging from 0.2 mph to 0.7 mph. The most notable difference is Matt Harvey, who gains 0.7 mph on his four-seam fastball with the new system. The reason for this appears to be because Harvey gets less extension off the mound than most Mets pitchers, so he releases the ball a little further from home plate.
It's also possible that the radar measurements could vary from ballpark to ballpark based on where the Trackman system is located. Baseball Prospectus found equipment bias to be a problem with Statcast’s exit velocity.
So when Mets fans are checking velocity numbers this season, it’s notable to know what the source of the reading is, because the new Statcast velocities featured in Gameday will be higher than PITCHf/x velocity readings from previous seasons.