Ronald Acuña Jr.’s Kryptonite: Heat

Ronald Acuña Jr. is one of the best young players in baseball. His 9.9 bWAR, 130 OPS+, and .897 OPS through his first two seasons put him on the fast track to the Hall of Fame. The man is 22 years old, a true wunderkind in today’s game, and a franchise cornerstone for the Atlanta Braves.

But he can’t handle the heat.

Even the greatest players on the planet have flaws, and Acuña Jr. is no different. He is one of the fastest men in MLB, has a decent glove, a rifle for an arm, and enough bat-to-ball skills to overcome his legitimate struggles with high velocity. Because they are quite real. Let me walk you through the numbers.

Gas him up

Ronald Acuña Jr. saw 539 pitches over 95 MPH in 2019. His numbers against those offerings were, in a word, bad. By bad, I mean a .177 batting average with a .270 wOBA and 31.7 K%. I mean a .173 xBA and a .355 SLG. I mean a 85.5 MPH average exit velocity and .177 ISO. Really bad.

But hey, everyone struggles to hit those pitches, right? Velocity always plays. If the hitter has less time to judge the pitch and swing the bat, it makes it more difficult for him to be successful. It’s simple. The problem is, Ronald Acuña Jr. was one of the worst hitters in the league against these pitches, regardless of how inherently difficult they are to handle.

Of the 195 MLB hitters that saw 200 or more pitches over 95 MPH in 2019, Acuña Jr. ranked 162nd in xOBA, 177th in xBA, and tied for 185th in exit velocity. He is firmly entrenched among the very worst in the game when it comes to handling the fastest of fastballs, and this fact has become well-known in opposing clubhouses.

Ronald Acuña Jr. saw more pitches above 95 MPH in 2019 than any other player, by a margin. His grand total of 539 is 13% higher than the next highest total, which belongs to Bryce Harper, who faced 477 and generally tattooed them (.298 BA, .521 SLG, .389 wOBA). Acuña Jr. saw these pitches 17.7% of the time, which was, once again, one of the highest totals in the league. He had a great 2019, finishing in the top-five in NL MVP voting, but hard-throwing pitchers had their way with him most of the time.

What’s the problem?

Ronald Acuña Jr. does not have a typical MLB swing. The head of his bat is far more vertical than many of the game’s other great players, as many hitters have it at around 45 degrees and slightly coiled around their heads after their load. He also creates a huge amount of space between his body and his hands as he strides forward. You can see all of this in the slow-motion video below.

Now, here are a few of today’s other stars. Notice the positioning of their hands and the angles of their bats. They are coiled, less vertical, and have less ground to cover due to their hands being closer to their bodies.

What does this all mean?

It means his swing tends to get a bit long and loopy, which makes it difficult to barrel up high-velocity pitches. This type of swing does help him stay on off-speed stuff, or pretty much anything around the knees. He has abused those offerings throughout his career. But hitting a 98 MPH fastball is especially difficult for a player whose hands are so far away from him and whose bat is so vertical.

Every hundredth of a second matters for hitters, and Ronald Acuña Jr. sometimes wastes a few too many by having such an elongated swing.

Does it matter?

Ronald Acuña Jr. probably doesn’t have to change a single thing in his swing in order to end up in Cooperstown. Though there are some issues that have revealed themselves through his horrific numbers against elite velocity, he has more than enough hand-eye coordination and athleticism to be a star with his current swing.

HOWEVER…there is a chance he does need to change things up.

Acuña Jr. better get used to the heat because it isn’t going anywhere. Velocity and high spin rates will always be in high demand, and those are both things that he continues to struggle with. Although the 2020 season is only a handful of games in, Acuña Jr. has once again seen more pitches over 95 MPH than any other player, with 31. He is hitting .000 against those pitches. He has yet to put one of them in play. His K% is 100%. He’s seen them a whopping 29.5% of the time.

Small sample size? Absolutely. Acuña Jr. will certainly improve from his horrific start. But this is a sign that his inability to barrel up the gas has carried over into 2020, and that teams are taking full advantage right from the get-go.

Ronald Acuña Jr. is, objectively, among the best players in the game, regardless of age, but his swing might need to be tweaked if he is to ascend to the level of the Trouts, Yeliches, and Mookies of the world.