How Ronald Acuña Jr. can reverse his slow start

April 29th, 2024

Let’s start with a caveat: Ronald Acuña Jr. will almost certainly start hitting like Ronald Acuña Jr. before too long. It could be today, it could be tomorrow. But it's very, very likely to happen.

Second caveat: This prediction is based on his track record — the unanimous NL MVP Award last season, the four All-Star appearances, the three Silver Slugger Awards — and not what we've seen so far in 2024. Because what we've seen in the first month of the season has been pretty un-Acuña-like.

Though most hitters would give just about anything to have Acuña's still-excellent .382 on-base percentage, the rest of his hitting stats this season contain some real head-scratchers (all numbers below are through Sunday's games). Consider:

  • His .333 slugging percentage is his second-lowest mark in any of the 27 months during his career in which he’s collected at least 50 plate appearances (behind only July 2022, in his first season back from a serious knee injury). His only other month below .400 was May 2018 — his first full month in MLB.
  • Discounting overlapping spans, this is only the second time in Acuña's career that he has hit no more than one home run over a 26-game stretch. The other also came in 2022, when he was admittedly playing timidly after his ACL surgery in 2021.

These struggles basically boil down to three things:

  1. He isn't hitting the ball as hard as usual.
  2. His ground ball rate has surged.
  3. He's whiffing a lot more than last year.

Add it up, and it makes for a frustrating formula for one of the most electric players in the game, even if it hasn’t held back the Braves (who still lead MLB in OPS and runs scored per game). So how can the Acuña of 2024 return to his world-beating 2023 form? Here is a closer look.

Square it up, in the air

For starters, Acuña's hard-hit rate is the lowest it's been outside his rookie year, at 47.2 percent. While that is still solidly above the MLB average, it’s well below Acuña's typically elite level. Last season, when he made history with baseball's first 40-70 season, his hard-hit rate was 55.2 percent, among the best in MLB.

But even a hard-hit ball typically needs to be a line drive or fly ball to do damage. However, when Acuña has made contact this season, it's usually resulted in a ground ball. His grounder rate so far is 54.2 percent, by far his highest rate ever and about 11 percentage points higher than his career average of 43.3 percent.

Given all those grounders, Acuña's fly ball rate has taken a significant hit in 2024, falling to just 15.3 percent, a bottom-five number among MLB regulars. The fly balls he has generated have an average exit velocity of just 91.7 mph, resulting in just two hits (a homer and a single).

With less hard contact and more balls on the ground, it follows that Acuña's barrel rate — which measures the sort of optimal contact that tends to produce extra-base hits — is at an astonishing career-low of just 8.3 percent. His previous career-low barrel rate was 12.8 percent in 2022.

Acuña's barrel rates, past five seasons

2020: 16.0 percent (95th percentile)
2021: 20.3 percent (99th percentile)
2022: 12.8 percent (88th percentile)
2023: 20.3 percent (93rd percentile)
2024: 8.3 percent (60th percentile)

Given that about 86 percent of home runs hit across MLB come on barreled balls, it’s clear that Acuña will need to find his way back to that sort of contact before he can become a 40-homer threat again.

Get the whiffs back in check

Though Acuña's strikeout rate of 24.4 percent this season is only a little above both his career average and the 2024 MLB average, it's more than twice what it was last season, when he achieved an historic decline in that metric. And though he's had other seasons when his strikeout rate was significantly higher (29.7 percent in 2020, for example), he was still hitting the ball hard when he made contact, which helped offset all the whiffs (see his .987 OPS in 2020). But that's not happening so far in 2024.

Acuña's whiff rate this season — how often he misses when he swings — is 29.6 percent, his second-highest ever. But what's surprising is how he's whiffing: Basically, he's consistently missing pitches in the strike zone AND he's chasing pitches outside the zone with greater frequency than normal. And when he chases, he's making contact a lot less than usual.

Specifically, Acuña's having more trouble with fastballs than with any other pitch in 2024. Though he's actually missing breaking pitches at a higher rate (33.9 percent to 29.9 percent), his whiff rate on fastballs is more than twice what it was in 2023.

If the peak-level Acuña of 2023 is going to reappear here in '24, it’s going to be in part because he rediscovers his ability to put the bat on the ball, especially against heaters.

The aforementioned issues with both the quality and quantity of contact explain why his expected batting average and expected slugging percentage are .268 and .394, respectively. Those figures are somewhat in line with Acuña's actual numbers.

In other words, he's not just hitting into bad luck. Improvement will have to come from within.

What to make of it all

How can a guy who seemed so otherworldly last season when he established the 40-70 club be so ... off? Several things to keep in mind:

  1. It's still early. It's been 26 games. It's important to not get too invested in the dramatics of Small Sample Size Theater, seductive as they may be. Everything we know about Acuña tells us this is almost certainly just a mirage. All those career accolades didn't just materialize out of nothing.
  1. A minor knee injury interrupted Acuña’s Spring Training, keeping him out of game action for more than two weeks, and once he returned, he had time to appear in only eight games before Opening Day. It's very possible he's just not all the way "trained" yet in 2024 on big league pitching. In other words, he might still just be a tick off on his timing or his mechanics.
  1. It's not the knee. Acuña has been insistent that his knee isn't bothering him at all. His 11 stolen bases — including one that set an Atlanta Braves record — lend excellent evidence to support that. So while some of his early 2024 numbers may share eerie similarities with that timid 2022 performance, it appears to be merely coincidental.
  1. Baseball is just weird. Sometimes things just happen that defy explanation. Slumps happen, even to the best. But also, a guy can look like a fraction of himself for a month and then return to form and win an MVP Award. It's just the way it is. That doesn't mean Acuña will end up replicating his 2023 output, but we definitely shouldn't rule it out.

For now, though, it's just a matter of waiting. Given Acuña's history, his fly ball rate is certain to increase, as is his contact rate, as is his hard-hit rate. When that happens, his homer and slugging totals are likely to rise — perhaps rapidly.

Don't worry, Braves fans. Even though Acuña is starring in a quite unfamiliar and surprising role so far in 2024, his scene-stealing ways are likely to return soon. It's just that in Small Sample Size Theater, the drama can seem, well, dramatic.