Four-Seam Fastball Whiff Leaders Across MiLB In 2023
Image credit: Kyle Harrison (Photo by Jayne Kamin-Oncea/Getty Images)
No matter how much the sport tries to escape, minimize or pocket it, there’s no denying the fastball is still the style of pitch most synonymous with pitching. The value of a good fastball has never been more important than it is today, even despite fastball usage steadily declining across all levels of baseball.
Baseball has become obsessed with fastball velocity, shape, spin and movement. This has sparked a dialogue around fastball characteristics that years ago were hardly discussed. This perspective has gone mainstream in recent years.
Paul Skenes is a great example. The Pirates selected the LSU righthander No. 1 overall this July. Skenes was one of the most dominant college starters ever in 2023. Yet his fastball was picked apart by some because it lacks bat-missing shape.
Fastball Velocity Gains In 2023
These pitchers showed significant velocity gains this season and are breakout candidates entering 2024.
All this to say, fastball quality matters. A good scout will say that it’s not how hard a pitcher throws or even how they throw it — it’s what the hitters tell them. What does that mean? Simply put, if hitters miss a pitch at a great rate or seem fooled by it, that’s an indication of pitch quality.
Today we take a look at the pitchers with the highest whiff rates against their four-seam fastballs. We’ll discuss the common traits and characteristics across the players listed below as we look to gain insights on fastball quality. The minimum sample to qualify for this list is 400 fastballs thrown.
When looking at overall performance, all of the pitches listed below performed at an above-average rate in 2023. Every pitch on this list produced a positive run value this season and no pitch on this list produced an XWOBA above .345. The average XWOBA across the sample was .292, and the average strikeout rate of each pitcher included was 34.7%.
The ability to miss bats with your fastball is a key component of overall success for a pitcher, but it’s not everything. It’s simply a piece to the puzzle for prospects looking to earn long term roles in the major leagues. Inclusion on this list does not guarantee a major league career.
Whiff Rates Against Four-Seam Fastballs
| Player | Level | Org | T | Vel | IVB | HB | VAA | Whiff% | K% |
| John McMillon | AA | KC | R | 97.5 | 18.9 | 8.6 | -4.3 | 45.5% | 45.27% |
| Julian Bosnic | A+ | PIT | L | 90 | 18 | -6.8 | -5.1 | 44% | 31.02% |
| Pedro Garcia | AA | CIN | R | 94.5 | 17.1 | 8.2 | -3.8 | 43.5% | 33.48% |
| Peyton Alford | A+ | SEA | L | 93 | 21.8 | -10.3 | -4.4 | 43% | 36.41% |
| Jesus Rivero | A | MIL | R | 90 | 16.4 | 10 | -4.0 | 42.5% | 32.54% |
| Paul Gervase | AA | NYM | R | 94 | 16 | 9.9 | -4.8 | 42% | 38.55% |
| Tyler Thornton | AA | CLE | R | 92.5 | 15.7 | 10.8 | -3.3 | 42% | 37.26% |
| Jacob Heatherly | AA | CIN | L | 95 | 16.7 | -11 | -4.5 | 41% | 38.24% |
| Ignacio Feliz | AA | BAL | R | 93 | 16.4 | 6.3 | -3.9 | 40.5% | 28.23% |
| Kyle Harrison | AAA | SF | L | 94 | 13.1 | -14.3 | -4.0 | 40.5% | 36.21% |
| Emmet Sheehan | AAA | LAD | R | 96.5 | 18.4 | 11.8 | -3.7 | 40% | 40.96% |
| Graham Firoved | A+ | BAL | R | 92 | 20.3 | 5.7 | -4.9 | 39.5% | 24.21% |
| Dan Hammer | AA | BAL | R | 94.5 | 18.9 | 2.6 | -4.3 | 39.5% | 36.36% |
| Drew Gray | A | CHC | L | 92 | 17 | -8.6 | -4.6 | 39% | 36.36% |
| Matt Merrill | A | WSH | R | 93.5 | 16.4 | 10.5 | -4.4 | 39% | 35.33% |
| Steven Perez | ROK | CLE | L | 91.5 | 18.1 | -3.7 | -5.0 | 39.00% | 29.17% |
| Hayden Harris | AA | ATL | L | 91.5 | 15 | -8.4 | -3.9 | 38.5% | 36.84% |
| Jace Beck | A+ | NYM | R | 93.5 | 19.1 | 7.1 | -4.9 | 38.5% | 38.51% |
| Dayeison Arias | AA | SEA | R | 93.5 | 13.6 | 3.4 | -4.6 | 38.5% | 26.41% |
| Peter Van Loon | AA | BAL | R | 94 | 16.9 | 9.6 | -4.7 | 38.5% | 29.05% |
| Jordan Leasure | AAA | CWS | R | 97.5 | 18.9 | 6 | -4.3 | 38% | 38.35% |
| Christopher Troye | AA | BOS | R | 94 | 20.9 | 2.1 | -4.6 | 38% | 39.55% |
| Stevie Branche | AA | CIN | R | 95.5 | 16 | 13.2 | -4.1 | 38% | 31.12% |
| Tyler Mattison | AA | DET | R | 95 | 20.2 | 5.1 | -5.0 | 38% | 37.92% |
| Natanael Garabitos | A | SEA | R | 97.5 | 17.9 | 11.6 | -4 | 38% | 30.17% |
So what have we learned from that chart?
Velocity Matters
The average velocity between the 25 leaders is 93.7 mph. Of the 25 players listed on the leaderboard, nine of the 25 averaged under 93 mph on their fastball in 2023.
But It’s Not Everything…
While fastball velocity is key, generating ride and flat vertical approach angles on your fastball seem to be equally important. Of the 25 players listed the average induced vertical break is 17.5 inches, nearly an inch above the major league average for induced vertical break on a fastball.
Flat Approach Angle Matters… A Lot
Of the 25 fastballs listed above, 14 have a VAA below -4.5 degrees. Anything below this number is considered to be a flat approach. To go a step further, this list contains eight fastballs with a VAA flatter than -4.1 degrees. Anything below -4.1 is considered truly outlier release. Very few fastballs generate plane flatter than -4.1 degrees. Pitchers like Jacob DeGrom, Paul Sewald and others are prominent examples. Among fastballs that were thrown 400 times or more this season, only 21 fastballs had a VAA flatter than -4.1 degrees, meaning nearly 40% of the fastballs with a VAA flatter than -4.1 degrees ranked within the top 25 in fastball whiffs.
Velocity Is Less Important If Pitchers Have Outlier Traits
There’s four pitchers on this list that average below 92 mph on their fastball. Two average more than 18 inches of induced vertical break and the other two have outlier vertical approach angles. These four pitchers–Pirates LHP Julian Bosnic, Brewers RHP Jesus Rivero, Guardians LHP Steven Perez and Braves LHP Hayden Harris–all have outlier traits that allow their fastballs to play above their velocity.
Relievers Rule When It Comes to Whiffs
This shouldn’t come as a surprise. Pitchers can air it out in shorter stints. It doesn’t take a significant amount of research to identify that. However, there’s four pitchers in this list that made double-digit starts this season and maintained high whiff rates. They are the Giants LHP Kyle Harrison, Dodgers RHP Emmet Sheehan, Cubs LHP Drew Gray and Orioles RHP Peter Van Loon.
