Comparing Spring Training & Regular Season Fastball Velocity
David Frerker-Imagn Images
In a recent article, I wanted to show the average fastball velocity increase from Spring Training to the regular season. I went to Mike Fast’s classic article, “Spinning Yarn: Do Spring Speeds Matter?” at Baseball Prospectus, and noticed it was 15 years old. In the article, he found a 0.6 mph increase from Spring Training to the regular season. As much as I trust Mike’s work, it’s time for an update. After looking at the numbers, the velocity difference has shrunk to almost zero.
To find the change, I took the available Spring Training fastball velocities from the past three seasons for both sinkers and four-seamers. Then I calculated the average and median differences, along with the standard deviation. Additionally, it seems like relievers are down more than starters (>=50% GS/G in regular season) in Spring Training, so I split them up.
That’s pretty much it, so here are the results.
| Pitch (Role) | Average | Median | SD | 1 SD (68% chance) | 2 SD (95%) | 3 SD (99%) |
|---|---|---|---|---|---|---|
| FF (All) | 0.26 | 0.22 | 0.94 | -0.7 to 1.2 | -1.4 to 2.4 | -2.0 ti 3.6 |
| FF (SP) | 0.08 | 0.07 | 0.87 | -0.8 to 0.9 | -1.6 to 1.9 | -2.4 to 2.8 |
| FF (RP) | 0.37 | 0.34 | 0.96 | -0.6 to 1.3 | -1.2 to 2.7 | -1.8 to 4.0 |
| SI (All) | 0.18 | 0.13 | 0.89 | -0.7 to 1.1 | -1.4 to 2.1 | -2.1 to 3.2 |
| SI (SP) | 0.01 | 0.01 | 0.81 | -0.8 to 0.8 | -1.6 to 1.7 | -2.4 to 2.5 |
| SI (RP) | 0.29 | 0.24 | 0.92 | -0.6 to 1.2 | -1.3 to 2.4 | -1.9 to 3.6 |
The overall increase is cut in half from the original study, with starters seeing almost no increase … on average. All the standard deviations approach 1 mph, so there can be some major differences from one pitcher to the next. I included the velocity ranges for different standard deviations. In the best-case scenarios (3 SD), starters gain about 2.5 mph while relievers are adding 4 mph.
With that knowledge, feel free to navigate our player pages to see who is up and who is down. And for me, it’s back to Mining the News.
Jeff, one of the authors of the fantasy baseball guide,The Process, writes for RotoGraphs, The Hardball Times, Rotowire, Baseball America, and BaseballHQ. He has been nominated for two SABR Analytics Research Award for Contemporary Analysis and won it in 2013 in tandem with Bill Petti. He has won four FSWA Awards including on for his Mining the News series. He's won Tout Wars three times, LABR twice, and got his first NFBC Main Event win in 2021. Follow him on Twitter @jeffwzimmerman.
Where on the player pages can you find spring velo? I looked but couldn’t find it.
I clicked on “pitch type and velo” on the right side. For the 2026 season the level is “ST”
Thank you!