HOW MUCH BETTER IS A 96MPH FASTBALL THAN A 95MPH FASTBALL?
I recently went to a baseball game and while watching the Rockies get absolutely rocked I was reminded of an analysis I did some number of years ago where I tried to identify how much a mile per hour matters for a pitcher in baseball.
I reread my analysis and thought I could make some improvements mostly on the software and data side -- so I'm happy to present some up-to-date figures with stronger datasets.
Let's jump in. These are graphs derived from every four seam fastball thrown between 2018-2025 in the MLB to try to answer the question "How much better is a 96mph fastball than a 95mph fastball?"
Contact goes down when speed goes up
Players swing more often at faster pitches
Players swing and miss more at faster pitches
Faster pitches result in fewer runs
Conclusions:
A 96mph four seamer is roughly 1 percentage point harder to hit, swung at 1.1 percentage point more often (0.76 percentage point for a miss) than the same pitch at 95mph. Per 100 pitches the one mph results in 0.18 fewer runs.
Pretty interesting! Just for fun, here are the individual pitchers who gain the most or least from the velocity change:
