Yandy Diaz is an exceptional hitter, but he may not yet have reached his potential. Despite an impressive physique and top tier exit velocity, Diaz lacks the in-game power that usually is associated with either of these qualities.

To look into what Diaz does well and where he might be able to improve, let’s begin with the following video of Diaz hitting a bases loaded single — a line drive off a pitch inside.

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On first glance, you may not like what you see.

Beginning with the mound perspective, you might see a swing where the hitter’s body appears out of sync. Diaz begins his leg motion early, in comparison to when the pitch will reach the plate, and accordingly gets to the ball seemingly early.

This can give the appearance that Diaz is simply muscling the ball into a single, using his strength to hit the ball a little farther than the average bear.

However, Diaz does two things that allow him to be a very successful hitter that are particularly easy to notice when using the side profile:

First, his direction away from his body and through the ball is fantastic. His swing, moreover, is fairly short and direct, and he’s able to control the direction of his barrel.

Coincidentally, the player traded for Yandy Diaz struggled with just these very skills. Jake Bauers’s direction was dependent on the shape of his swing (more on that below). This is not a problem if you can put the barrel on the ball, but for Bauers, that ability ebbed and flowed in 2018.

Diaz, by comparison, is not only able to put the barrel on the ball, but is able to hit through the ball and (in this case) into center field. Diaz’s ability to send this inside pitch up the middle comes from directing his spray with purpose. That is an elite barrel-to-ball skill.

Secondly, Diaz is able to keep his bat in the plane where the pitch is thrown. In this instance you might see that he reaches the ball out in front of the plate (which is good!), but even if he didn’t, there’s enough plane in his swing to hit the ball even if it were deep in the zone.

For players like Bauers who struggle with this, the bat swings around their body as opposed to dropping into the zone and swinging through it. That change in approach is what unlocked J.D. Martinez’s swing and is an important step to becoming an elite hitter.

Indians hitting coach Ty Van Burkleo praised this quality of Yandy Diaz’s swing last April, describing Diaz’s swing as having “plane”:

“There is plane to his swing. It’s just he catches the ball very deep and he has the ability to accelerate to the ball very deep, which allows for low trajectory, high velocity balls off the bat.” [mlb.com]

In other words, Diaz gets his bat behind the ball early, as opposed to swinging down on top.

To fully illustrate the trade off being made by the Rays in this... uh... trade, here’s an example swing by Jake Bauers that looks great in a spreadsheet; he bats a pitch down the middle with 100 mph exit velocity:

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Bauers swings down over the ball, achieving a good result but without plane. As is the story for most major leaguers, it works but it needs improvement.

By comparison, Diaz is not hacking at anything. He’s ready to make contact early in his swing because his bat path sets him up for success — whether he’s pulling the ball or going opposite field.

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Diaz’s swing on this pitch middle-away is as high level as it gets. An inexperienced player can only reach and flick when the is ball away or when timing in hitting is off. And even though Diaz appears to take an early stride again, he relatively launches the ball.

And yet, it still falls short.

Why?

Recognizing that Diaz is already a productive and talented hitter, we will use the rest of this article to discuss areas for improvement that may help Diaz unlock his full potential.

1. Stop Leaking Power

In every video we see Diaz take an early stride.

An early stride is not a problem; Diaz is not hitting flat footed, which would be the initial concern. Furthermore, an early stride that is controlled is fine, but the problem might be that Diaz doesn’t wait long enough for the pitch with his lower body.

A hitter gains power and trajectory by staying coiled in the back leg, but Diaz really gets into his front leg, even on pitches inside, which hitters typically track longer. They do this by effectively dropping low while weight is still on the back leg. Here’s an example of Miguel Cabrera doing just that:

Cabrera is striding forward, but his power has not yet transferred to his front leg.

By staying in the rear leg until the swing starts, the hitter is able to adjust to the pitch with “stretch” left in their body. If the hitter shifts forward into the front leg before the swing, their back side has leaked power.

Burkleo correctly notes that Diaz definitely gets the barrel behind the ball beginning deep in the zone. This is challenging for hitters, and Diaz does it well — but it’s especially tough while leaning into the front leg. That observation should make Diaz’s relative production at the plate all the more impressive.

Here’s the moment of power transfer in the hips from the first Diaz swing above:

Notice how Diaz has his front hip engaged. He has released the stretch from his rear leg and hip, and has begun to transfer weight to the front leg. His power has leaked.

This analysis is the definition of nitpicking, and the change being described is quite difficult to accomplish because it depends on the player’s mobility in the hips and desire to tweak at such a granular level.

It suggests, however, that the key to unlocking power for Diaz is less likely to be associated with something like “launch angle” and more likely to be associated with his weight distribution. Unless he improves the coil of power in his rear leg, his ceiling is limited.

2. The Inside Pitch

Another thing worth mentioning about Yandy Diaz’s swing is that he approaches pitches inside like they are pitches middle or away.

Consider again the side profile we studied above:

This single comes off a pitch inside.

With the pitch in, the hitter has to get his hands inside the pitch and allow for the barrel to work in a direction through the ball. The only way Diaz’s barrel gets to that ball is if he swipes across the plane with his hands before going through with the bat.

Diaz still gets to the ball in front of the plate, but he makes contact in line with his knee, as opposed to making contact out near his leading foot.

That’s pretty much what a hitter “getting jammed” is. Diaz just has such a quick, strong swing that he is able to muscle that ball out of the infield. If that’s a player of Matt Duffy’s stature using the same swing had the same at bat as the GIF above, it’s a weak ground ball to short.

Diaz is just freakishly strong.

For Diaz, it’s great the he can consistently handle pitches no matter their location, but an inability to pull his hands inside could spell trouble down the road.

Case in point, consider a similar swing to Diaz: Yasiel Puig.

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It’s not a 1:1 comparison.

Diaz gets the barrel into the zone deeper than Puig, who tends to be more down in his path through the ball. That is why his average isn’t as high as Diaz, but when Puig reaches the ball perfectly (which he frequently does), he catches back spin and missiles it — often out of the park.

By catching the ball farther out front, Puig gets better lift, but this approach also makes it harder to for the hitter to adjust.

Between the two, Diaz has the safer approach but half the ISO, so perhaps Puig’s approach is better. You’ve gotta risk it to get the biscuit. But this similar swing does reveal the possible weakness that Diaz could develop on inside pitches.

Consider Puig’s average exit velocity map:

The bad news is that column of blue inside is to be expected with this sort of swing.

The good news is that pitchers tend to be reluctant to pitch inside. Going too far in and hitting batters, especially when the majority of batters stand nearly on top of the plate, is giving away free bases; moreover, if a pitcher makes a mistake trying to go inside, the pitch likely ends up right down the middle. Like this:

You don’t want to give one of those to Puig or Yandy Diaz.

Diaz can continue to hit his way and remain productive. But he might struggle with the pitch in and also struggle with power unless improvements are made, either toward Puig’s approach or toward Cabrera’s — and note: neither of those improvements are related to “launch angle.”

Here’s something that is, though: posture.

3. Posture

With Diaz’s posture the way it is, unless he catches it out front, his path is too flat to lift the ball. Because Diaz is already into his front hip, his trunk/torso/upper body will struggle to get his barrel going uphill from deep in the zone. It’s the kinetic chain of events.

In other words, yes, he doesn’t swing up enough to be a homerun hitter. Take a look at Diaz’s only homerun in the major leagues:

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Diaz hits the cover off the ball, but struggles to get his barrel going uphill from deep in the zone, and the resulting longball comes from brute strength. It doesn’t take a hitting coach to diagnose that problem, but we cannot just say “launch angle” is the answer.

The reason it’s not a simple fix to “hit the ball in the air” through an improved launch angle is because, without the fix in the rear leg and hip (and in turn with Diaz not able to fix posture), swinging up hill more is just an unnatural movement.

In order to stay adjustable, Diaz has to catch the ball deeper with his bat path. This creates a long swing plane but also a flat one, and it hurts his ability to lift the ball or get to the pitch inside with as much authority. As a consequence, nothing is getting launched.

If Diaz hits it far, it’s all muscle.

Additionally, it’s not clear whether urging hitters to consider launch angle is helpful.

For some, thinking about it may actually force them to get to the right movements. So as weird as it sounds, telling Diaz “hey, we want you to hit fly balls to left field all day today” could potentially help him, because it forces him to get inside of the pitch more and get the barrel to a better spot.

For others, thinking launch angle is an awful thing, leading to drastic changes in process that make hitters less successful.

The Indians are the hub of launch angle experimentation. It’s likely the coaches in Cleveland have already tried this approach, and that Diaz’s answers lie elsewhere. It’s also possible the right method of communication has just not come about.

Daniel Robertson was able to improve his launch angle in 2018 by focusing on his hands as a way to “getting on plane with the baseball,” which resulted in launch angle improvements but was not the stated goal.

Conclusion

In closing, it’s interesting to note that Diaz’s spray chart is exactly what you’d think it would be, knowing what we already know:

When Diaz pulls the ball he is frequently grounding out, likely as a result of battling pitches inside. Baseballs hit the other way lack home run distance.

Yandy Diaz is already a great hitter, and that’s why the Rays gladly swapped five years of Bauers for five years of Diaz.

His hands and direction are very good, and recent video evidence shows that Diaz makes solid contact through the ball and out in front of the plate, so there seems to be little cause for concern that his bat won’t be productive.

However, with his issues in his rear leg/getting into his front hip, he basically has no choice but to hit the ball out front. This leads to a lack of “lift” on pitches away, despite his solid direction and strength.

If you’re looking for a player who has already found a road to major league production at the plate, Diaz is certainly a safer bet than Bauers, even if it’s with a lower ceiling with his swing as-is.

If Yandy Diaz doesn’t change, the Rays will still be happy with who they’ve got: a player who already hits the ball hard. But like Bauers, there might be potential to unlock even more. For a team that thinks their playoff window is opening, choosing Diaz over Bauers isn’t as crazy as it sounds.

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Curt Wilson is a professional hitting consultant working out of Square Up Academy in Bradenton, FL. He has worked with high school, college and pro hitters from 16 different MLB organizations.