In his first 36 starts this season, Ronald Acuña Jr. batted in the Braves’ cleanup spot every game and acted accordingly, which is to say he barely ran despite his natural speed. Cleanup hitters aren’t typically built for base stealing, but Acuña is not built like a typical cleanup hitter: He’s young and lean and a capable center fielder, and he ranks in the top 6 percent of MLB base runners in sprint speed in 2019, just behind noted speedsters Billy Hamilton and Mallex Smith, and just ahead of Mike Trout and Fernando Tatís Jr.
And yet Acuña ran more like a catcher than like Hamilton while hitting in the middle of Atlanta’s lineup. After those 36 games, he had just two steals—fewer than Yasmani Grandal and as many as Yadier Molina at that point—and although he was still reaching base and hitting for power and doing everything asked of him in the field, he wasn’t quite optimizing his five-tool skill set, either.
But the next day, in an effort to jumpstart a stagnant lineup, Braves manager Brian Snitker pushed Acuña to the leadoff spot, and the reigning Rookie of the Year took to his new role with gusto. He’s still reaching base, and he’s still hitting for power, and he’s still doing everything asked of him across all three outfield spots—and now he’s running, too, like almost no other player in the majors. Since May 10, the first day Acuña batted leadoff, he is tied with Seattle’s Smith for the most stolen bases in the majors (32). And now he is just three homers and six steals away from the fifth-ever 40/40 campaign.
Acuña is not the only National League star en route to combinatorial history. In Milwaukee, reigning MVP Christian Yelich is six homers shy of the majors’ first 50- homer, 30-steal season, after a three-steal Saturday brought him up to the latter benchmark. As home runs fly at a record pace, stolen bases have dropped to their lowest point in nearly half a century, which make Acuña’s and Yelich’s seasons all the more impressive. At least a couple of players are capitalizing on the juiced ball while keeping the stolen base alive.
Viewed across MLB history, the high homer/steal combination is a relatively recent phenomenon. Entering 2019, there had been 62 30/30 seasons in MLB history, but just one of those campaigns came before Willie Mays pulled the feat in consecutive years, in 1956 and 1957. That one player was the St. Louis Browns’ Ken Williams, who paired a league-high 39 homers with 37 steals in 1922—but he was an aberration, as nobody else managed even a 25/25 season before Mays. (Williams was an aberration in more ways than one; he was also the only non-Yankee to lead the AL in home runs in any year from 1920 to 1931.)
Home runs and stolen bases don’t tend to mix, either on a leaguewide or individual level. The 19 highest stolen base years, on a per-team per-game basis, came from 1901 to 1919—the deadball era—when a lack of power meant small-ball tactics were more effective in producing runs. But stolen bases dropped precipitously through the 1920s and 1930s, as home runs rose for the first time, and stayed at that depressed point for decades after. It was hard for anyone to produce notable homer/steal combinations for the first half-century of MLB play precisely because the high-steals athletes played before high home run totals were possible, and the high-homer sluggers played after high steals totals had disappeared.
The same downward pull on stolen bases is occurring now, in the highest homer era in league history. The league’s steal levels haven’t stooped quite to where they were in the previous century’s downturn, but the 0.46 steals per game that MLB is averaging in 2019 is the lowest rate since 1971. And because analytics have emphasized the avoidance of outs, thus raising the importance of stolen base success rates, steal attempts are on an even sharper decline. (Unsuccessful steals weren’t reliably tracked until 1920, thus the red line’s late start in this graph.)
The connection between home runs and steals is intuitive: If anyone in a lineup can hit a home run at any point, any given stolen base is less valuable because runners will score on a homer regardless of their base state. That relationship means that the break-even success rate to make a steal attempt “worth” trying is higher in high-homer seasons. Yelich exemplified this notion the last time he was caught stealing, in the first inning against the Pirates on July 6, when catcher Elias Díaz nailed him trying to take second one pitch before Brewer teammate Mike Moustakas homered, so Milwaukee scored just one run instead of two.
The decline in stolen base value in the present day is exacerbated by a steep decline in singles, because the simplest way to turn a steal into a run is to take second base and then score on a single. But the 10 lowest-single seasons in MLB history are all the seasons from the 2010s, with 2019 at the bottom. There has essentially never been a less effective offensive environment in which to run.
Individually, moreover, the kind of player who can frequently steal bases is rarely the kind of player who can hit bushels of home runs. The top stolen base totals this decade belong to Juan Pierre (career high in home runs: three) and Dee Gordon (four), while the top home run seasons belong to Giancarlo Stanton (career high in steals: 13, which is the only time he went higher than six) and José Bautista (nine). In MLB history, the average 40-homer hitter steals just 7.7 bases; the average 40-base stealer hits just 7.9 home runs. That disparity is what makes high combinations so special, and the 2019 stat lines for Acuña and Yelich such a thrill.
Let’s take their potential achievements one at a time. Acuña would join José Canseco, Barry Bonds, Alex Rodriguez, and Alfonso Soriano as the only members of the 40/40 club. A 40/40 season, then, is rarer than a 60-homer season. It’s rarer than a 100-steal season. It’s such a remarkable pairing of two disparate, often oppositional skills that only 10 players have accumulated both 40 home runs and 40 steals in any season, let alone the same one: Bonds, Rodriguez, Mays, Brady Anderson, Soriano, Canseco, Trout, Vladimir Guerrero, Carlos Beltrán, and Ryne Sandberg.
Yelich’s potential accomplishment is naturally even more rare. Only Larry Walker in 1997 (49 homers, 33 steals) and Soriano in 2006 (46 homers, 41 steals) have come within real striking distance of a 50/30 season. And only five players have managed both 50 homers and 30 steals in any two seasons of their careers: Bonds, Rodriguez, Mays, Anderson, and Sammy Sosa. Trout could join that club if he hits five more home runs this season to reach 50.
In Troutian fashion, Yelich’s extraordinary offensive season only looks more impressive when folding in baserunning alongside his ample production at the plate. If anything, his status as the best hitter in the National League has obscured his stolen base skills. FanGraphs’ calculations rank Trout and Yelich first and second in runs produced with a bat this season, and fourth and third, respectively, in runs produced via baserunning. (This latter measure includes three factors: stolen bases, double plays, and extra base advancements—for instance, going from first to third on a single.) Yelich has been caught stealing only twice all year—his 94 percent success rate would rank in the top 10 all-time among players with so many steals—and he isn’t afraid to pursue riskier ventures. He is tied for second in the majors with seven steals of third base.
Both players have a good chance to reach their respective milestones, though as the end of the season approaches, neither is guaranteed. At his current pace, if Yelich plays every game remaining on Milwaukee’s schedule, he’d expect to finish with 50.9 home runs. Acuña would expect to end with 41.7 homers and 38.3 steals (or, using just his steal rate as a leadoff man, 39.5 steals). More than a home run, though, a steal relies largely on intentionality; Acuña probably approaches every plate appearance seeking a home run, but he doesn’t necessarily look to steal every time he reaches first base. If he finds himself just one or two short of 40, though, he might be more likely to run.
From a pure value perspective, 40/40 and 50/30 don’t necessarily represent the best possible numbers for a player; a homer is worth significantly more than a steal, so something like 55 homers and zero steals would produce more runs in 2019’s run environment. But an elite power/speed profile has two advantages over a comparatively more valuable but more one-sided stat line.
First is that a notable power/speed combination is still plenty valuable. Past precedent shows that to record even a lesser homer/steal combination season is to, in all likelihood, put forth an All-Star-level campaign. The homers and steals themselves help, of course, and the sort of player who can reach these dual benchmarks is liable to contribute in other areas, as well, such as being fast and athletic enough to play solid defense. This chart shows the season outcomes for every pre-2019 player who reached a certain homer/steal threshold.
Power/Speed Season Outcomes
|HR/SB Combo||Number of Seasons||Median WAR||Percent of Players Above Average|
|HR/SB Combo||Number of Seasons||Median WAR||Percent of Players Above Average|
Second, and more centrally to any discussion of Acuña and Yelich, is that a more diverse set of skills is incredibly entertaining. Many of baseball’s most exciting players combine power and speed, along with other tools, and these two NL stars bring daily thrills and anticipation to their fans. In any at-bat, they can hit a home run; at any point they reach base, they can accelerate in an instant, such that every pitch matters.
That quality is particularly enthralling in an era so short on overall daring on the base paths. Even teams ostensibly built on speed, like this season’s Royals, have eschewed heterodox baserunning tactics. After adding Billy Hamilton and Terrance Gore in the offseason, Kansas City looked poised to steal 200 bases or more—instead, Hamilton and Gore have both been released, and the Royals are on pace for a mundane 121, which would have been below the league average throughout the 1980s.
Even in this extreme home run era, it’s possible that stolen bases could make something of a return in the coming years, in the cyclical fashion that most baseball statistics have manifested over the sport’s history. As Michael Baumann explored for The Ringer earlier this year, as catchers are selected more for framing than throwing skill, eager base stealers might be able to prey on weaker arms behind the plate. And if any new rules come to MLB, baserunning strategies could shift as a result. In the first month of the Atlantic League’s rules experiments this season, which included slightly larger bases and a requirement that pitchers step off the rubber before transitioning to a pickoff move, stolen base rates rose an astounding 73 percent, from 0.8 per game to 1.4.
But even if stolen bases creep back upward leaguewide, it’s unlikely that many players will match 2019 Acuña or Yelich. Such is the height of their possible achievement, which in Acuña’s case has little precedent and in Yelich’s has none at all. It was already clear the two were special players. Just look at their hardware from last season; just look at how both are already on reasonable Hall of Fame trajectories in their 20s. Still, it’s nice to have a statistical signifier of just how special they are, as standouts not just in their era, but in the entire annals of the sport.