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Atlanta Braves hitting trends: Ronald Acuna

By Alan Carpenter

SARASOTA, FLORIDA - FEBRUARY 20: Ronald Acuna Jr. #13 of the Atlanta Braves looks on during a team workout at CoolToday Park on February 20, 2020 in Venice, Florida. (Photo by Michael Reaves/Getty Images)
SARASOTA, FLORIDA - FEBRUARY 20: Ronald Acuna Jr. #13 of the Atlanta Braves looks on during a team workout at CoolToday Park on February 20, 2020 in Venice, Florida. (Photo by Michael Reaves/Getty Images) /
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ST LOUIS, MISSOURI – OCTOBER 07: Ronald Acuna Jr. #13 of the Atlanta Braves hits a double against the St. Louis Cardinals in game four of the National League Division Series. (Photo by Jamie Squire/Getty Images)
ST LOUIS, MISSOURI – OCTOBER 07: Ronald Acuna Jr. #13 of the Atlanta Braves hits a double against the St. Louis Cardinals in game four of the National League Division Series. (Photo by Jamie Squire/Getty Images) /

About Acuna

He’s still just two months beyond his 22nd birthday and is already drawing age-and-performance-based comparisons to some of the game’s greatest players… yet he outwardly appears not only unaffected by the attention, but actually thriving on it.

If you were to take today’s career stats over his 267 games played and extrapolate them to a 17-year career of 150 games per season, you’d get numbers like these:

  • 640 home runs (this would rank him 7th all time)
  • 1576 RBI (45th all time)
  • 506 stolen bases (37th all time – tie)
  • 1958 runs scored (10th all time)
  • 2884 hits (41st all time – tie)

Of course that’s all assuming that he has a constant performance trajectory, but it’s also a reasonably conservative timeline, which includes missing over an entire season of games in that hypothetical 17 years (Acuna played 156 in 2019).

So what we’re witnessing is Hall-of-Fame-level output today, but the bigger question is this: can he maintain that… or even improve?

That’s why digging into the numbers may provide some clues about how Acuna is adjusting as a hitter thus far.

It’s still early. We only have about one-and-two-thirds seasons of data thus far, but it’s certain that pitchers are paying close attention to their own results when facing Acuna, for they will be more motivated to adjust even than he is.

So what are opposing pitching sending Acuna’s way over the period 2018-19?

  • FASTBALLS.
    • These have been increasing. We’ll see why shortly.
    • 52.9% in 2018; up to 56.2% last season.
  • SLIDERS.
    • A corresponding drop here…
    • Down from 22.2% to 19.6%
  • CUTTERS.
    • Not a big ticket here: roughly 6% both seasons.
  • CURVEBALLS.
    • Slightly down from 9.5% to 8.5%. Not terribly significant.
  • CHANGEUPS:
    • Virtually identical so far… holding at 8.5/8.6 percent.
    • Other pitch types (or unidentifiable): 1.5%

Characterizations

BrooksBaseball.net believes Acuna has a steady approach at the plate with all pitch types offered; a sharp contrast with his buddy Ozzie Albies, who is very aggressive all the time.

Against non-fastball pitches, Acuna does not have exceptional contact results, but does have good results: he has a league average whiff rate against breaking stuff (33%) and below chances to whiff against off-speed pitches (26%).

The surprising part involves fastballs. While his swing-and-miss rate against them looks to be about the same (26%) as these other pitches, Brooks calls that ‘Exceptionally High’ compared to the rest of the league.

In other words, if you have a good fastball – particularly one that have some movement or can be well located – you have a chance to get this hitter out.

That said… it’s a 26% chance to miss… not 80%… 90%. He’s still going to do some damage.

But do the numbers suggest that he’s doing any better at contacting fastballs as he’s going along?

Here’s the fangraphs data:

  • OSwing%
    • A steady approach generally means ‘more disciplined’ and Acuna swings at balls outside the strike zone 3% less often than his peers.
  • OContact% – So when he swings at wayward pitches, what happens?
    • When he does go after them, he’s making contact at a league-average rate
    • Of note: this was 3% lower in 2018… so there’s some improvement at hitting ‘bad balls’
  • ZSwing%
    • We saw some fairly incredible numbers for Albies here… turns out that Acuna is right with him:
    • 2018: 72.8% swing rate on strikes. Albies was at 73.4% during his first season in the majors.
    • 2019: A big jump to 82.7%… and that’s just above where Albies sits today.

So even though Acuna has some fastball troubles, it clearly isn’t all pitches or all strikes… he does make swings on strikes at a very high rate… suggesting excellent pitch location recognition.

  • ZContact%
    • Here’s the magic number, though: does Acuna make contact with swings on these strikes?
    • 85.6% is the average… and Albies was up to 87% over the past 2 seasons.
    • Acuna… a worrisome 71.5% rate 2018… however…
    • the contact rate jumped up to 80.0% last year.

That ZContact rate is clearly still below average, but the change in 2019 shows a strong move to improve.

There’s some more to look at here that adds context.

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