Welcome back to another round of scouting lingo! If you’re new here, be sure to check out the first installment of the pitching visual scouting primer, which includes an introduction to this series, along with parts one, two, and three of the hitting visual scouting primer, to catch up on what I’ve already covered.

In this installment, we’re making our way back to the mound to delve into the rich world of pitch shapes, specifically those of four-seam fastballs. As usual, much of this may be familiar to you, but my hope is that these visual examples can serve as a reference for the various ways we distinguish between different pitch shapes in scouting reports.

Four-seam fastballs are the most common and traditional type of fastball. When a pitch is described as a fastball, without any further qualifier, that fastball is a four-seamer more often than not. The name derives from how the pitch is thrown, with the grip employed, along with the backspin created when the pitcher releases it, causing four seams to cross the front of the ball as it’s rotating toward the hitter. Here’s what Clayton Kershaw’s four-seamer looks like after he releases it, with the four seams labeled as they cross the front of the ball on its way to the plate:

While the name is derived from this seam orientation, which is considered the standard, the classification has more to do with that distinctive backspin. For example, based on the spin illustration of Orioles closer Félix Bautista’s four-seamer on Baseball Savant, we can assume that he orients the seams differently than a traditional four-seamer. As a result, in contrast to the Kershaw GIF above, only two seams will come across the front of the ball as it’s traveling to the plate:

Still, the ball exhibits virtually perfect backspin, which indicates that Bautista is releasing the ball with his fingers behind it (sometimes referred to as “staying behind the ball”) and lets the ball roll off of his finger tips, without snapping his wrist around the ball in either direction, which prevents it from being classified as a two-seamer (more on that in a future installment of this series). The verticality of his hand, combined with the over-the-top arm slot he employs, creates that nearly perfect vertical backspin.

Here’s what that looks like in action, first all the way through, and then with freeze frames where you can see the seam alignment of his grip and the over-the-top release without a wrist snap:

That verticality will shift depending on a player’s arm slot, despite still releasing the ball with the pointer and index fingers behind it and without a wrist snap. As a result, four-seamers’ shapes vary widely, and with that variation comes terminology (and specific measurements) to help distinguish between them.

Four-Seam Fastball Shapes

Ride/Carry: Félix Bautista

Ride and carry are used interchangeably to describe the illusion of gravity-defying upward movement on a four-seamer. All fastballs drop to some degree, since they’re thrown from atop the mound to a target (the strike zone) situated lower than where the pitcher is standing. But the ones that drop less than a hitter’s instincts would have them expect (or an observer’s, for that matter) are referred to as having ride and/or carry. According to Baseball Savant, Bautista’s four-seamer featured the least downward movement in the majors in 2023, averaging just 7.2 inches of drop, which is less than half of league average (roughly 15 inches) and almost two whole inches fewer than the second-place Pete Fairbanks’ heater (9.1 inches).

Induced Vertical Break, or IVB, aims to quantify a pitcher’s ability to fight gravity. The current trend across baseball is to use four-seamers to hammer the upper part of the strike zone, so the ability to create the illusion of ride can be a valuable asset for a pitcher, as it will result in hitters swinging under a pitcher’s fastball. In Bautista’s case, there are a number of factors that contribute to the ridiculous IVB he creates on his four-seamer, including his staggering height, nearly triple-digit average velocity, and a higher spin rate than the average big league four-seamer. But when IVB is created on a pitch that is not thrown from such a height (Bautista is 6-foot-5), or with as much heat or spin, the illusion can be even more mind-boggling, and more confounding, to an opposing hitter.

IVB: Nestor Cortes

Cortes’ four-seamer lives in the low 90s, with spin rates more on par with league average. Cortes also stands under six feet tall, so the difference between the movement he gets on his fastball and what hitters would expect from that height and in that velocity band is quite drastic. As a result, Cortes’ average IVB in 2023 was 19 inches, which is much closer to that of Bautista (19.9 inches) than one might expect (the league average was around 15 inches).

Not all four-seamers feature this type of seemingly upward movement. The different shapes often have to do with the differing hand positions and arm slots employed by different hurlers. Without getting into the sports science behind how these shapes are created, let’s go rapid-fire through some other frequently used terms that describe different four-seam fastball shapes.

Run/Tail: Hunter Greene

“Run” and “tail” both refer to horizontal movement toward a pitcher’s arm side, like this one from Greene.

Cut: Max Fried

Inversely, when “cut” is used to describe a four-seamer’s shape, it refers to horizontal movement toward a pitcher’s glove-side, as exemplified by Fried’s heater. This is different from a “cutter,” which is thrown with a different type of spin, resulting from a different grip and wrist movement, and which I’ll dig into in a future entry to this series.

Sink: Tanner Houck

“Sink” is pretty self-explanatory, referring to downward vertical movement when it’s used to describe a four-seamer. Similar to the cut/cutter distinction, this is not the same as a “sinker,” which I’ll also discuss further in a future installment.

Uphill vs. Downhill

These terms refer to the plane of a pitch based on the release point used by the pitcher; determining factors are typically arm slot and the pitcher’s height, though the length of their arms can also come into play. Uphill will also sometimes be referred to as “flat,” whereas downhill will sometimes be described as “steep.”

Uphill, High Arm Slot: Clayton Kershaw

Though Kershaw throws from a high arm slot, and his arms aren’t particularly short, he lowers his release point with his drop-and-drive delivery, such that he’s able to create an uphill plane on his fastball.

Uphill, Short Arms: Adam Macko

Macko’s mechanics are also of the drop-and-drive variety, though they aren’t as extreme as Kershaw’s. Still, because his arms are quite short, the Blue Jays prospect has a similar release point to Kershaw, and therefore a similarly uphill plane.

Uphill, Low Arm Slot: Kyle Harrison

Harrison uses a drop-and-drive delivery (are you noticing a pattern here?), but he further enhances his uphill plane by way of a significantly lower arm slot.

Downhill, High Arm Slot: Tyler Glasnow

Given that the above examples of uphill planes are created by drop-and-drive guys, it’s no surprise that downhill planes are, almost definitionally, created by tall-and-fall deliveries. Glasnow, who stands at 6-foot-8, further steepens his plane with a high arm slot.

Downhill, Low(er) Arm Slot: Cole Irvin

Given the angles necessary for a downhill plane, it’s virtually impossible to create one from a lowered arm slot, unless the pitcher is on the taller side. Irvin’s arm slot is about as low as you’ll see produce a downhill plane.

Having only covered four-seamers, there’s much more to get into when it comes to pitch shapes. My next installment (or, more realistically, my next two) will move into the rest of a pitcher’s arsenal, as well as how different pitch shapes can play off of one another to enhance a pitcher’s overall effectiveness. See you then!

Source