Ronald Acuña, Free Swinger

Ronald Acuña had Steve Cishek right where he wanted him. He had worked the count to 3-0, and with a man on first base, Cishek was in a tough situation. The Cubs led by only two, and that put Cishek in quite the bind. Walk Acuña, and the tying run would be aboard with no one out. Give him a pitch to hit, and the game could be tied in a single swing. Acuña waited, Cishek dealt, and the result:

Cishek, no doubt, made the exact pitch he was hoping for. Still, it was a tremendously aggressive swing from Acuña, at a pitch that he couldn’t do much with. No real harm done — Acuña walked on the very next pitch. Cishek, as it turns out, was wild that day — he’d walked Freddie Freeman before Acuña, and he walked Nick Markakis after him to load the bases. All three scored, and the Braves won. Still, what was Acuña doing swinging there? Cishek had thrown seven straight balls to start the inning. The Braves weren’t punished for Acuña’s aggression, but the swing seemed a bit out of place.

A mere six days later, Acuña worked himself into another 3-0 count. The situation wasn’t quite as dire for pitcher Seunghwan Oh, but 3-0 counts aren’t good for pitchers under any circumstances. Oh dealt, and Acuña was ready for it:

Again, the plate appearance ended in success; this time, Acuña laced a 3-2 cutter to center for a single. This pitch was at least in a location Acuña could do damage on. Still, bases empty and only one out? That’s the ideal time to be taking all the way. That’s a valuable situation for a walk.

Hey, I hear you saying that this isn’t very interesting, really. This is merely two cherry-picked examples of a batter swinging on 3-0. Look at all of baseball, and you’re sure to find something like this, even if the batter isn’t particularly aggressive. Heck, Juan Soto, Acuña’s age-20 counterpart and plate-discipline god, swung at 3-0 pitches on back-to-back days this year. Acuña’s two swings are nothing special, in other words.

It’s true! Nothing about Ronald Acuña swinging twice on a 3-0 count seems interesting. I wouldn’t try to convince you that it was. Here’s the thing, though. Acuña hasn’t swung at two 3-0 pitches this year. We’re not talking about three pitches, not four, not five, not six, not seven. Ronald Acuña has swung at twelve 3-0 pitches this year. If that sounds like a lot to you, you’re absolutely right. No one in baseball has swung at more 3-0 pitches this year. In the past five years, the highest full-season tally of 3-0 swings is Joey Votto’s 18 in 2017, a mark Acuña could easily surpass. Acuña has only seen 20 3-0 pitches this year — he’s swinging at a colossal 60% of them.

Votto’s presence atop the leaderboard is a good sign that swinging 3-0 isn’t a mark of poor plate discipline. Votto didn’t swing at a single pitch outside the strike zone among the 18 pitches he offered at; he simply swung at strikes to keep pitchers from getting an automatic strike every time the count went 3-0. Is that what Acuña is doing — honing in on a certain part of the zone and going after it to keep pitchers honest?

In a word, no. Three of his twelve swings have been at pitches likely to be ball four. Take a look at this swing against Steven Matz and decide for yourself whether that’s an area he was waiting to ambush:

No, Acuña isn’t sitting on a particular pitch. He’s not even really looking high or low — he’s swung at as many pitches on the bottom of the zone as the top. Acuña is just content to swing at anything he thinks he can hit. One way to think of it is this: on every pitch that isn’t 3-0, Acuña swings at 67% of the pitches he sees in the strike zone. That’s right around league average. On 3-0 pitches, he’s swinging at 75% of strikes — more, certainly, but nothing out of the ordinary. Pitches out of the zone? He swings at 24% of them on every count but 3-0, and 33% on 3-0. Given the small sample, it’s hard to say he’s changing his behavior at all.

Having your normal swing percentages on 3-0 counts is, in and of itself, abnormal. Major leaguers as a whole basically don’t swing on 3-0, whether the pitch is a strike or not. They swing at 14.8% of pitches in the strike zone on 3-0, as compared to 67.6% in all other counts. Chases on 3-0 are even less frequent — 4.3% of 3-0 pitches out of the strike zone draw swings, compared to 28.7% of pitches the rest of the time. By remaining the same, Acuña is incredibly different.

Okay, so Acuña’s behavior on 3-0 is pretty weird. Does it work, though? Well, that’s pretty hard to say. There are a few levels you could look at. First, the actual swings he’s taken this year haven’t worked out at all. In twelve swings, he’s gotten five swinging strikes, six foul balls, and a pop up to shortstop. You don’t need me to tell you that’s bad — none of them are hits!

On the other hand, Acuña’s production after reaching a 3-0 count this year has been tremendous. He’s posted a 283 wRC+ after 3-0 counts, well above the MLB average of 245. As the encounters with Cishek and Oh demonstrated, he’s perfectly capable of wasting a swing on a tough pitch and still coming out ahead. He’s still walking 45% of the time after reaching 3-0, which is below the league average of 60% but still totally acceptable, and striking out only 5% of the time. The production plays, in other words, even if he’s getting to it in weird ways.

Still, the question remains: why do it? This is a totally new phenomenon for him — he swung only three times on 3-0 pitches last year, all of them fastballs in the strike zone. He swung at around 20% of 3-0 pitches in the minors as well. It’s not a symptom of changing his plate approach, either — his overall in- and out-of-zone swing rates are more or less unchanged from 2018. I don’t think it can be chalked up to a small sample size — swinging on 3-0 is one of the things that hitters have the most control over. BABIP might take forever to stabilize, but deciding whether you want to swing isn’t like that.

We’re deep into guesswork here, because Acuña hasn’t spoken about it, but I have a likely culprit. You see, while Acuña didn’t swing very frequently at 3-0 pitches last year, he made the most of those swings. His second swing was just a good baseball play, putting a ball up in the zone into the air with a man on third and one out. It worked a little bit better than “good,” though:

What happened next? Well, Acuña took four straight 3-0 pitches, three of them for called strikes. Then he took another swing, and he was rewarded again (and good god, the Marlins attendance problems are clear in this GIF):

For the season, Acuña swung at only 3 of 11 pitches in the strike zone on 3-0. He was, in other words, basically average when it came to swing rate. His production, meanwhile, was otherworldly. Major leaguers in 2018 posted a .494 wOBA when they put the ball in play on a 3-0 swing. They also whiffed on 17% of swings and fouled off another 40%. That’s 57% strikes, 43% high-value balls in play — that ratio works. Acuña, though — wow. He didn’t foul any pitches off. He didn’t swing through any. He compiled a 1.093 wOBA when he swung at 3-0 pitches and a .628 wOBA after taking 3-0. Who could blame him for wanting to alter the mix a little?

I’m comfortable saying that Acuña has taken his 3-0 aggression a little too far. Getting that fourth ball is incredibly valuable, and Acuña has swung at a few likely balls on 3-0 this year. At the same time, though, maybe he’s onto something. It hasn’t worked so far this year, but getting your hacks in on 3-0 has some merit. Maybe the production hasn’t been there on those swings this year, but it certainly was last year, and the overall line (40% foul rate, 33% whiff rate, .820 wOBA on balls in play) is attractive.

Is swinging on 3-0 the next market inefficiency? Probably not. But it hasn’t kept Acuña from having a tremendous 2019, and it’s given pitchers one more thing to worry about. Let’s put it this way: if you’re a pitcher facing a 3-0 pitch to Ronald Acuña, just grooving the ball in there isn’t going to cut it. At the same time, his production hasn’t really taken a hit. He’s plenty capable of buckling down on a 3-1 count and accepting a walk. For now, it’s merely a curiosity to watch. 3-0 pitches are boring most of the time, but not when you’re watching Acuña.