Behind Ronald Acuña Jr.’s MVP campaign: The homers and steals aren’t even the wildest stats for the Braves superstar
Acuña is on pace to found the 35-homer, 75-steal club, but another number shows his ascent into the stratosphere of historic hitters
Atlanta Braves outfielder Ronald Acuña Jr. might go down as the face of MLB’s 2023 season. In a year that will be synonymous with rule changes designed to stoke more action, Acuña is baseball’s foremost action hero.
The favorite for NL MVP ahead of former teammate Freddie Freeman and current teammate Matt Olson (because Braves), Acuña has a case headlined by big, shiny numbers. He has 27 homers and an MLB-best 55 stolen bases through 119 games. The only player with even 25 homers and 25 steals so far this season, he’s on track to found the 35/75 club.
The escalating power-speed counters have Acuña earning comparisons to Rickey Henderson, Eric Davis and Joe Morgan — three of the eight members of the 25/50 club that Acuña has already joined. That very fun lens, however, might be too narrow to provide an accurate look at the leadoff dynamo’s offensive omnipotence.
In 2023, Acuña is batting .338 and leading baseball in on-base percentage, at .423. He ranks second in MLB in FanGraphs WAR, behind only Shohei Ohtani. What’s more, underneath the black ink and throwback speed numbers, Acuña’s 2023 greatness stands atop a major improvement that could level up his game with or without the speed element.
Namely, Acuña has sliced his strikeout rate in half. If such a thing can go relatively unnoticed, this has. The 25-year-old superstar — a former Rookie of the Year and five-time All-Star — entered this season with a career 25.3% strikeout percentage, a touch above league average but well within normal range for a power hitter who also draws plenty of walks. This season, Acuña’s K% is down to 12.2%, seventh-best out of 140 qualified hitters. Unsurprisingly, he has a higher walk rate, better on-base percentage and more home runs than anyone ahead of him on that list.
Braves manager Brian Snitker attributed Acuña’s seismic strikeout rate change to experience — to a young, “electric” player learning how to tackle the challenges of the major leagues more consistently.
“I think that's maturity and experience,” Snitker said recently, “just the confidence that guys have as they become older and they play the game longer.”
This is not a ho-hum manifestation of maturity, though. Acuña’s strikeout rate improvement between 2022 (23.6%) and 2023 (12.2%) is not only the best in MLB this season; it’s also the largest season-to-season change since Ryan Klesko in 1998 (minimum 400 plate appearances per season).
And without even a normal amount of strikeouts as a release valve, Acuña has become nigh unpitchable. Braves catcher Sean Murphy, asked how he might devise a sequence to retire his teammate, just shook his head and smiled.
“I'm happy he's on my team,” Murphy said. “It doesn't look like there's too many things you can do, reliably, to get him out.”
How did Acuña make half his strikeouts disappear?
Prior to this season, the best way to get Acuña out, relatively speaking, had been to entice him with fastballs up and away.
Since 2019, his second MLB season, Acuña has been one of the sport’s preeminent breaking ball mashers in an era when that’s a great thing to be. But after a terrific rookie campaign of fastball-hunting, his fastball production hadn’t quite matched up. Between 2019 and 2022, he batted .262/.372/.499 against fastballs (which we’re defining as four-seamers and sinkers only), which comes out to a .372 wOBA. That’s pretty good, but most major-league hitters make their hay against fastballs, so it ranked only 92nd out of 239 hitters who saw at least 2,000 fastballs in that span.
Against everything else? Against the breaking and offspeed pitches that stymie most hitters? Acuña slashed .285/.362/.521 for a .375 wOBA that ranked third, behind only Mike Trout and Yordan Alvarez.
The reason behind the disparity mostly came down to something simple: Acuña made less contact against fastballs than most hitters but more contact than average against breaking and offspeed pitches.
In 2023, he has changed that dramatically. Through 2022, Acuña had a 24.4% whiff rate against fastballs. This year, he’s missing on just 13.9% of swings against heaters and batting a career-best .337 against them.
The how of it all is difficult to trace to any one thing, though Snitker’s experience theory is a decent umbrella term. There are a couple of signals that point toward a more nuanced approach at the plate. Against those fastballs that often caused him to swing and miss — with high and outside pitches being his most common bugaboo — Acuña has clearly turned to a contact-oriented swing more often in 2023. That shows up in a lower average launch angle, more balls to the opposite field or up the middle, and more balls on the ground against fastballs.
In other words, more of Acuña’s swings against high fastballs look like this:
That’s not inherently good. For a lot of players, this wouldn’t be worth the homers and doubles sacrificed in the endeavor. But it’s a useful trade-off when you are Acuña-level fast (so you can steal extra bases) and Acuña-level powerful (so you can slug against more favorable low fastballs and breaking balls).
This year, Acuña has sacrificed a touch of slugging from his previous best seasons (2020 and 2021), but the extra value provided vastly outweighs the cost. The first, most obvious boost comes from his reaching base so much more often, and he then creates more value by burning up the basepaths.
The less immediate improvement is in situational hitting, a critical segment of the game in which Acuña is now wielding a more robust toolbox. He’s the second-best two-strike hitter in MLB this year and significantly better than he had ever been in tough counts. In high- or medium-leverage situations, Acuña is batting .370 with a 184 wRC+, which in turn means he’s tracking toward his best season by win probability added.
Putting Acuña’s offensive game into historical context
If anything of note is lost in this shift, it might be Acuña’s ticket to the 40/40 club, which he came so close to joining with a 41-homer, 37-steal 2019 campaign. That said, the rest of the numbers should more than make up for the missing home runs.
Using FanGraphs’ plus stats, which adjust the numbers for baseball’s wildly variant eras, we can get a bird’s-eye view of Acuña’s season. Take that improved strikeout rate: 12.2%, an elite mark today that would’ve been merely average for much of baseball history. Gauging Acuña’s excellence requires that context. His K%+ would’ve been about 100 in 1977, but in 2023, it’s 55, meaning 45% better than average (lower is better in this statistic).
Since integration, only nine seasons (from six hitters) have matched or bested Acuña’s current combination of on-base percentage (131 OBP+), slugging percentage (138 SLG+) and strikeout rate (55 K%+) dominance compared to the MLB norms of the time.
Albert Pujols (2009, 2008)
Barry Bonds (2004, 2002)
Todd Helton (2000)
Wade Boggs (1987)
George Brett (1985, 1980)
Stan Musial (1948)
None of those seasons, by the way, involved more than 16 stolen bases. But the implications of this list exist outside the running. They hint at a new gear, a new magnitude for Acuña’s still-rising star that could definitively lift him above contemporaries such as Juan Soto, Fernando Tatis Jr. and Vladimir Guerrero Jr., even as age saps some of the stolen base enthusiasm.
If Acuña can maintain these eye-popping gains in the batter’s box, we might remember 2023 not as the year he created a new power-speed club but as the first year of a new and somehow improved Ronald Acuña Jr.
