A Visual Scouting Primer: Hitting, Part Three

Welcome back for another installment of FanGraphs’ Visual Scouting Primer! For previous editions, or an introduction explaining the concept of this ongoing series, you can click here, here, and here, but in an effort to tamp down my word count, I’m diving right into it this time.

Fluid vs. Stiff

Generally speaking, these terms are pretty self-explanatory, but perhaps it’s worth providing some clarity for how they are applied to describing baseball swings.

Fluid: Mookie Betts

As you can see, Betts’ body moves like liquid, sending energy from his bottom half to his top. The movement and rotation in his body moves seamlessly from his legs to his shoulders, in a way that reminds me of the crack of a whip, and ripples upward through his entire body. The Gumby-esque fluidity includes ample hip/shoulder separation, which I covered in a pitching context in the first entry to this series, but which applies to hitting in a similar way. His hips open up while his shoulders and hands stay back, before his upper half follows suit, and his arms shoot through the zone, due to this energy transfer.

Stiff: Giancarlo Stanton

If Betts is Gumby, then Stanton is a GI Joe action figure, with only a handful of articulated joints. His movements are much more herky jerky, with his hips and shoulders moving in unison to rotate his entire torso as one block, while his strong arms muscle their way through the strike zone.

A side-by-side comparison only makes their differences more obvious.

Rotational vs. Non-Rotational Swing

These terms can be confusing, since every swing includes some degree of rotation. But for some players, the rotational nature of their swing is a key component of how they generate bat speed, and by extension, power.

Rotational Swing: Luis Matos

Matos’ swing is extremely rotational. While he doesn’t have the same hip/shoulder separation as Betts, the degree to which his entire midsection rotates from the start to the finish of his swing is impossible to miss. By the time he is done swinging, his bat is smacking his back, and it looks like he’s trying to show off his belt buckle to his teammates in the dugout. Meanwhile, the momentum of his rotation makes it so that he winds up on the outer side of his front foot. An ultra-rotational swing like that of Matos is likely to produce power only to his pull side, since there’s so much physics involved, and it’s difficult to time an opposite-field swing with this type of rotation, without being dangerously behind on the pitch.

Non-Rotational: Luis Robert Jr.

Robert’s swing never involves much rotation, but this is a particularly non-rotational example. Even on hacks when his midsection has more rotation, like when he rips inside pitches to his pull side, his swing is much more about brute force created by his upper body. His hips don’t rotate to nearly the same degree as Matos’ do, and sometimes hardly at all, with his belt buckle staying visible throughout his whole swing, from the side view. He stays more or less flat-footed, and hardly uses his lower half at all to generate his mind-boggling power, which only boggles the mind all the more. While the momentum of Matos’ bat virtually corkscrews him into the ground, Robert finishes with an abrupt halt to his bat, as though he suddenly decided to stop swinging.

Bonus Rotational Swing: Moises Ballesteros

Based on the above two examples, it may seem like this comes down to body type, with Matos’ leaner, wiry athleticism equating to an ultra-rotational swing, and Robert’s more filled-out frame employing a more physique-over-physics approach. But while that is often true, there are plenty of exceptions. Take, for example, Cubs prospect Moises Ballesteros, whose build is quite different from that of Matos. The way that Ballesteros creates an explosive rotation is quite impressive, as it belies his body type, and illustrates a level of athleticism that is somewhat less obvious or intuitive based on appearance alone (not to mention its impact on his exit velocities).

In the first installment of this series, I mentioned that a repeatable pitching delivery is even more impressive when it’s being done by a pitcher with long, lanky limbs. Ballesteros’ rotational swing is similarly impressive, as it’s less expected from a player with his build.

Grooved vs. Adaptable Swing

A grooved swing is one that can only generate consistent power when it follows a very specific bat path. These swings are easiest to pick out during batting practice, when players are trying to send everything out of the park. A grooved swing will look virtually identical every time, in this context. The concern with a grooved swing is that it usually includes a significant amount of swing and miss and/or noticeably weaker contact on pitches that don’t adhere to the specific part of the strike zone that the bat’s groove passes through.

Grooved Swing: Jasson Domínguez

For Domínguez, a switch hitter, his grooved bat path goes through the heart of the zone, about belt high. Before tearing his UCL in September and undergoing Tommy John surgery, Domínguez played eight career games in the majors and hit four home runs. They all came against pitches along that grooved path while he was batting left-handed, so we’ll only focus on his lefty swing for this analysis.

Here are some overlays of two of his big league home runs:

While Domínguez is able to make contact in other areas of the zone, his home run power is limited to that band across the plate, and his overall slash line is much higher in that band as well. When a pitch is in a zone outside of his pre-determined bat path, he does little, mechanically, to adjust his swing to the different zone.

It’s too early in Domínguez’s career to make any rash assumptions about how his home run power will change over the course of his time in the majors, but lest this seem like a small sample anomaly, here’s where all of Dominguez’s left-handed minor league home runs crossed the plate (viewed from the catcher’s POV):

It’s clear that at this point, his home runs are limited to that specific part of the zone, with very few exceptions. But he gets away with his grooved swing by making up for it with his keen pitch selection, and of course by being a switch hitter with other enviable tools.

Adaptable Swing: Julio Rodríguez

By comparison, here’s a look at all the locations of the pitches Julio Rodríguez sent out of the park in 2023:

Unlike Domínguez, Rodríguez’s visualization doesn’t clearly illustrate a specific zone where he’s obviously more proficient at producing home run power. This is because Rodríguez has a proven ability to adjust the mechanics of his swing, depending on the location of the pitch at which he’s swinging, without necessarily sacrificing power. Here are two home runs that Rodríguez launched on pitches that fall well outside of Domínguez’s power belt.


I won’t belabor the point: Rodríguez’s ability to adapt his powerful swing to pitches throughout the zone makes him, at this point in their respective careers, a more versatile power hitter than Domínguez.

Top-Hand vs. Bottom-Hand Dominant Swing

First, let’s define these terms. “Top” and “bottom,” in this context, refer to how the player’s hands are oriented on the bat. The hand closest to the knob is the bottom hand, and the hand closest to the barrel is the top hand. A right-handed hitter’s right hand is his top hand, and his left hand is his bottom hand, and vice versa for lefties.

These terms refer to which of a hitter’s hands is responsible for guiding his barrel through the zone, and/or providing it with power. Naturally, this isn’t always obvious; both hands, of course, are crucial to any given baseball swing. But there are specific mechanical differences between a top-hand dominant swing and its bottom-hand counterpart. Let’s take a look at some visual examples to hopefully make the distinction more clear.

Top-Hand Dominant Swing: Mike Trout

Trout’s swing is top-hand dominant because his right hand is the one responsible for controlling his barrel and providing his swing with its signature home run power. This is evidenced by the fact that his right arm stays bent and flexed throughout nearly his entire swing, with clear control over the path of the bat from start to finish. Another indication of this is that the palm of his right hand stays pointed upward until long after contact.

Bottom Hand Dominant Swing: Bryce Harper

Harper’s swing is bottom-hand dominant, and it’s not too surprising, considering he’s a righty who swings left-handed (i.e. his dominant hand is his bottom hand). To be sure, Harper’s top hand is still an important element of his swing. In the past, Harper has explained that his mental focus is on his top hand as he swings, and he’s described it as a hammer. The impact of that mental approach is evidenced by the fact that he can still be short to the ball, despite his bottom hand being the stronger of the two. Even so, his overall mechanics are those of a bottom-hand swing, which is true of many batters who throw righty and hit lefty.

In contrast to Trout, the arm of Harper’s top hand straightens out shortly after contact, as his bottom hand pulls the barrel of his bat through the zone, and his top hand rolls over the handle of the bat after contact, as opposed to remaining palm-up for as long as Trout’s does.

That’s a TL;DR version of the distinction between these types of swings, so, if you’re into the whole brevity thing, this can be your off ramp. But even with that understanding, identifying top- and bottom-hand swings in the wild can be a challenge, so here are a few more specific indicators to look out for.

Let’s start with side-by-side clips of their respective swings:

The elbow of Trout’s top hand stays connected to his torso when he makes contact, while Harper’s arms are already beginning to extend at the point of contact, and his top elbow is less connected to his torso. The angles of these slow-mo swings are just different enough to obscure this distinction. (The camera on Trout’s swing is positioned slightly behind the plate, whereas the camera for Harper’s is slightly in front of the plate.) Instead, here’s a different side-by-side comparison with more similar camera angles, which makes the difference in their arm extensions more obvious.

In addition to the differences in their arm extensions, right after contact, we can also see how the momentum of Harper’s bat pulls his hands over his right shoulder as he finishes his swing, whereas the control exerted by Trout’s top hand makes it so that his hands barely cross his chest. This may ring a bell, as it’s similar to the finish in Luis Robert’s swing above.

Indeed, torso rotation is often used differently for top-hand swings than it is for bottom-hand swings. In order for Harper’s bottom hand to guide the barrel of his bat to the sweet spot, his upper body needs to rotate more prior to contact, opening him more to the pitcher. He does this so that his right shoulder (the shoulder connected to his bottom hand) can be positioned in a way that aligns the sweet spot with its point of contact. To do this, Harper starts the rotation in his upper body much earlier than Trout does, and he is already rotating when his front foot lands after his leg kick. In contrast, since Trout’s top hand is the one controlling the barrel of his bat, he keeps his shoulders more square to the ball as he makes contact. Looking at their swings side by side from the pitcher’s perspective illustrates this difference.

After contact, Trout’s body begins to rotate more, which allows him to keep his top arm bent and flexed, as described above, while keeping the barrel of his bat in the zone for as long as possible. Conversely, by the time Harper makes contact, there’s not much more room for his torso to rotate. Instead, he keeps his barrel in the zone by fully extending his arms in order to push his hand through the zone, rather than keeping his arms tight to his body and rotating through the zone like Trout does.

Given Harper and Trouts’ respective track records, both methods are viable in terms of big league success.

Next time, we’re heading back to the mound for some more pitching terminology, but there’s plenty more to cover at the plate (and in the field!) too. So, if there are any terms that have had you scratching your head, don’t be shy about leaving them in the comments, and they may be featured in a future installment of this primer.