After the 2011 season, my relationship with baseball underwent a decisive transition from “Braves fan” to “baseball obsession.” Our once-whimsical romance suddenly looked like an episode of “You,” and I played a very convincing Joe Goldberg, never taking my eyes off the object of my heart’s desire.
So, what changed? One simple thing – someone introduced me to FanGraphs.
Exploring FanGraphs created in me a profound appreciation for the top players around the league. I found myself tuning in to watch Clayton Kershaw disembody hitters with his beautiful curveball, or to watch Andrew McCutchen’s deadly power-speed combo, or to watch Miguel Cabrera’s perfect approach and swing. When Trout broke out in 2012, I was a total goner.
And then – April 25th, 2018. Ronald Acuña Jr., top prospect, debuts at 20 years old. I watched as he notched his first base hit, a ground ball up the middle. The next day, he blasted a Homer Bailey slider into the second deck of Great American Ballpark as part of a 3-4 performance. All of a sudden, the league’s newest superstar had arrived.
By the time Acuña crushed that absolutely iconic grand slam off Walker Buehler in the 2018 NLDS, my jaw was perpetually sore from repeatedly hitting the floor for an entire summer. And while some continue to watch him and find things to complain about – the big swings and misses when he’s behind in the count, the occasional (and wildly overstated) lapses in judgement, and “all the jewelry” – I will continue to watch in awe as this absolute phenom makes an extremely difficult game look quite easy.
And the best part? He’s getting better.
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In 2020, Acuña made strides in his plate discipline, impact on contact, and defense. Let’s take a look under the hood.
Plate Discipline
Acuña showing improved plate discipline in 2020 certainly doesn’t fit the narrative that the Braves broadcast crew might have you believe, but it’s easy to see once you take a look.
Did the strikeout rate climb? Yes, from 25.9% K between 2018-19 to a career-high 29.7% in 2020. But his walk rate climbed much more, from 10.1% BB across his first two seasons to a staggering 18.8% in 2020.
That walk rate, which ranked 4th among all qualified hitters, was made possible by a change in approach:
| Year | O-Swing% | Z-Swing% | Swing% | Contact% | SwStr% |
| 2018 | 27.5% | 72.8% | 46.0% | 74.6% | 11.6% |
| 2019 | 26.7% | 71.5% | 45.3% | 74.2% | 11.6% |
| 2020 | 23.5% | 65.7% | 40.5% | 71.3% | 11.5% |
It appears that Acuña has simply chosen to swing less. In an ideal world, he would drop that overall Swing% by maintaining his in-zone swing percentage (Z-Swing%) and dropping his chase percentage (O-Swing%), but I’d imagine that’s easier said than done. While taking more strikes contributed to the uptick in strikeouts, the elevated walk rate makes it a worthwhile tradeoff, as evidenced by a career-high 159 wRC+ on the season.
Acuña doesn’t need to change a thing to continue being a fantastic baseball player, but it’s hard not to get excited about another potential evolution on the horizon. If he maintains his more passive approach from 2020 but regains his 2018-19 Contact% (percentage of swings that are not misses), his SwStr% (percentage of overall pitches that are swung and missed at) will likely dip down to the 9-10% range. If that happens, I’d expect his walk and strikeout numbers to come close to the 2019 version of Juan Soto (16.4% BB, 20.0% K), which would be an absolutely lethal improvement, considering his exceptional batted ball abilities.
Quality of Contact
As fans across MLB are well aware, Ronald Acuña Jr. has prodigious power. He had the longest HR of 2020, a mind-melting 495 foot blast that outpaced the year’s next-longest HR by a full 8 feet (nice try, postseason Luis Robert). But while all the simpletons out there find pleasure in looping replays of Acuña’s titanic tanks, educated fans like us can be thrilled simply by gazing upon the improved consistency of his batted-ball profile.
| Year | Barrel% | FB/LD
Exit Velocity |
Launch Angle | Hard Hit% | xwOBACON |
| 2018 | 13.4% | 95.3 mph | 13.1° | 46.6% | .480 |
| 2019 | 15.0% | 95.6 mph | 14.2° | 47.4% | .505 |
| 2020 | 16.0% (19th) | 99.5mph (3rd) | 18.6° | 57.0% (4th) | .526 (3rd) |
On the one hand, it shouldn’t be too surprising to see a player improve from their age 20-21 seasons to their age 22 season. On the other hand, this is quickly becoming ridiculous. He’s hitting the ball in the air more often, and he’s hitting those fly balls harder than ever. These strides, combined with the improved plate discipline, led to Acuña recording a career-high .581 SLG and finishing as one of only 9 hitters with an xwOBA over .400.
Anyway, here’s Acuña hitting the longest home run of 2020. Hey, could someone make a looping replay of Acuña’s titanic tanks?
Defense
Because it is so difficult to measure, defense can often be an underrated quality in Major League players. But anyone who watched the Dodgers go 13-5 in October on their way to a World Series championship can see how impact defense can change the direction of a game.
| Year | Innings | DRS / 1300 inn. | UZR / 1300 inn. | OAA / 1300 inn. |
| 2018 | 936 | 7 | -4.7 | 4 |
| 2019 | 1364 | 10 | 2.7 | -1 |
| 2020 | 376.2 | 14 | 8.3 | 7 |
| Career | 2676.2 | 10 | 0.9 | 2 |
Defensive metrics can be volatile and are most appropriately analyzed in sample sizes of 2-3 years, so Acuña’s career stats are the most indicative of his defensive abilities overall. But it’s difficult to ignore the fact that his pace in 2020 would have led to easy career highs in DRS, UZR, and OAA, and it’s a great sign that all three of these metrics agreed that he was above-average in 2020. Overall, we’re looking at a guy whose defense in the OF so far can be described as anywhere from slightly above average to plus.
One more note – positionally, Acuña’s worst numbers by DRS and UZR both come from his time in LF in 2018. Since he won’t be lining up there anymore, I anticipate his defensive performance over the next 2-3 years to be somewhere between his 2019 numbers and his 2020 numbers (which is to say, very good).
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There’s a perfect storm for Ronald Acuña Jr. to become a top 3 player in MLB. Combine his 2018-19 Contact% to his 2020 defense, impact on batted balls, and passivity at the plate. If he pulls that off – which would be a rare and tremendous outcome – it will likely thrust him near the Trout/Soto tier of hitters. This is awesome enough to imagine on its own, but when you remember that Acuña runs well and plays stellar defense…well, you can see why people talk about him as the type of guy who could become the top player in the game for many years.
One thing’s for sure – we’ll all be watching.
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