Swing Up, Stupid: How Statcast Fueled MLB’s Home Run Surge

Decades of conventional hitting logic are being set aside for one weird trick

Getty Images
Jun 05, 2017 at 1:47 PM ET

For as long as hitters can remember, coaches repeated the same refrain, ad nauseam: “Swing down on the ball.” This, it turns out, was not helpful advice.

After his midseason trade from the Reds to the Mets in 2016, Jay Bruce huddled with his new hitting coaches, Kevin Long and assistant Pat Roessler, and asked the question that had been gnawing at him for years, “How can I get the best out of my ability?” The Mets’ staff offered new perspective, telling the lefty slugger just how important it is to elevate the baseball and keep it off the ground. They assured Bruce that he has the most success when pulling a flyball to right-centerfield.

“My approach this year is,” Bruce said, “if I cannot hit it in the air, I do not swing at it.”

The simplicity of that plan is driven by the distillation of a dizzying array of information—“So many numbers and percentages and rates and ratios,” Bruce said. He’s a self-avowed infophile who used his newfound knowledge to tweak his natural swing, which had already powered 253 big league home runs.

With this air-or-nothing mantra in mind, Bruce has been (until a minor swoon after Memorial Day) on pace for the best season of his 10-year career by the two most popular summary stats for offensive performance—the more straightforward OPS and the wonkier wOBA. He knows that his flyball and hard-hit rates are at all-time highs and that, thanks to infield overshifts, the batting average for a ball pulled on the ground has fallen more than 40 points in the last decade to, Long said, a .186 average.

Bruce’s response? “Well, I don’t like that number.”

The idea of hitters unleashing more damage through the air has consumed the offensive narrative this season under the banner of “The Flyball Revolution.” Scoring and slugging reached two-decade lows in 2014 and, as recently as 2015, pitchers were using late movement at the bottom of the strike zone so much that ground-ball rates were at a record high.

Now, just two short years later, home runs are on an all-time record pace—at 1.23 per team per game, they even surpass the 1.17 mark from the year 2000, the height of the so-called Steroid Era—and the league-wide share of grounders has fallen in consecutive seasons for the first time in a decade. This season is on pace for 5,993 total homers, an increase of more than 1,800 since 2014.

What changed? As with all changes and trends in the eternal see-saw battle between pitchers and hitters, there was an adjustment—this one was unique, however, in that it was catalyzed by 2015’s proliferation of Statcast, Major League Baseball’s nascent radar-powered tracking technology. The plethora of data spewed out by the system includes the now-ubiquitous hitting buzzphrases “exit velocity” and “launch angle,” and the idea of the optimal power swing crystallized for many hitters. The language of change became accessible and these concepts entered the mainstream hitting vocabulary, facilitating more hitters to gear their swings for lift.

“I don’t think Statcast has necessarily affected what our coaches are teaching, [but] I think it does help give hitters a picture of what’s going on,” Giants general manager Bobby Evans said. “The information helps hitters understand the impact of adjustments. They’re in a more measurable and visual way.”

Astros GM Jeff Luhnow concurred, saying that the Flyball Revolution has not changed instruction, per se, but hitters’ understanding of their ideal offensive approach. The tool used to track performance is now powering it, too.

“When you’ve got guys on the internet analyzing trajectories and all the new information, there’s going to be a narrative that forms off of what they see,” Luhnow said, adding, “Now there’s a better model that coaches can articulate that uses this information, so if you’re not in your optimal spot, you now know what you need to do.”

Bruce, for instance, has raised the average launch angle of his contact from 14.6 degrees last year to as high as 18.3 in 2017 (and as high as 19.7 before his recent slump), what Long deemed a “significant” increase. Other hitters who have either transformed their games because of this thinking or have always been a devotee include stars like Kris Bryant, Jose Bautista, Josh Donaldson, and Long’s former Mets tutee, Daniel Murphy.

Across the majors, the average launch angle on all contact has risen nearly a degree in the last two seasons, from 10.0 in 2015 to 10.9 so far in 2017. Illinois physics professor emeritus Alan Nathan, who has extensively studied baseball, wrote at the Hardball Times that the optimal launch angle for a home run is 24 degrees, based on an estimate that the average fastball reaches home plate on a six-degree downward angle.

A search of Statcast data on the Baseball Savant shows that pitches either in the bottom third of the strike zone or below it were hit with an average launch angle of 4.5 degrees in 2015 but are now lifted at an average of 5.6 degrees—with a 29 percent increase in home runs on such low pitches, too. This affirms similar work done at FanGraphs showing that much of the league-wide rise in homers can be attributed to hitters’ improved results on low pitches.

Quite simply, as the Pirates’ new mantra states, “Your OPS is in the air.” Or, rather, as Donaldson quipped, “Just say NO…. to ground balls.”

A few players have reinvented themselves. Oakland A’s first baseman Yonder Alonso, for instance, who had never reached double-digit home runs or a .750 OPS in a full season, has slugged 16 homers with a 1.071 OPS this season after reworking his swing. His average launch angle more than doubled year over year from 10.3 to 21.9, although he denied that he is purposefully trying to elevate the ball. “Pitch selection, I think, is the most important thing,” Alonso said.

“We’ve been given the freedom to be who we are as hitters,” A’s teammate Khris Davis, whose 58 homers since the start of 2016 lead the majors, said. “We don’t go in the cage and [a coach] is like, ‘Hey, we need to work on your launch angle today.’”

Nationals first baseman Ryan Zimmerman has had a career renaissance while lofting the ball more this year, too, even if he also says it’s not intentional. After repeated inquiries from reporters, he deadpanned to ESPN, “All offseason, I worked on hitting the ball one-eighth of an inch lower and it’s totally paying off. I used lasers and computers, and every time I didn’t hit it one-eighth of an inch lower, my bat blew up so that I had to get a new one.”

Zimmerman’s teammate, Murphy, is one of the headliners for the revolution. A metrics-reciting wonk, Murphy worked with Long late in 2015 to lower his stance and emphasize his power through his lower half, which he unleashed that postseason and continued after signing with Washington. His 47 doubles and .595 slugging percentage led the National League, while his 25 homers bettered his career high by 11.

“If you look at the numbers and really break it down,” Long said, “you can see this transformation happening in real time.”

The first Statcast metric to permeate the baseball discourse and resonate with players, not just analysts, was exit velocity—the measure of how fast a baseball leaves the bat and a proxy for a player’s power.

“I can remember, about two or three years ago playing with the Dodgers, they started flashing exit velocities on the scoreboard to go along with pitcher velocity and the fascination our team had with exit velocities—to the point where hitters weren’t upset anymore about making outs,” Marlins catcher A.J. Ellis, a Dodger until August 2016, said. “They were just more concerned about their exit velocity.

“ . . . Sometimes I feel like we get lost in the shuffle of consistent exit velocity, consistent launch angle, and we’ve lost some of the competitiveness of a grinding two-strike approach, slapping the ball with two strikes, fighting things off, real situational hitting because we’re all chasing really, really strong measurable stats.”

Those metrics must work in concert with each other. Exit velocity means bupkis on its own, as Matt Holliday learned the hard way in 2016. Then with the Cardinals, the veteran outfielder ranked fourth in average exit velocity among regular players, trailing only Nelson Cruz, Giancarlo Stanton, and Miguel Cabrera, yet his production lagged far behind those stars.

“Exit velocity was great,” Holliday said, “but I hit .246.”

Holliday hit 20 homers with his own personal-low OPS of .782, owing largely to the downward trajectory of so much of his contact. His average launch angle was just 8.4 degrees, prompting a revision of his swing. He too had long been instructed to “have a short swing” and “swing down on the ball,” but he called that ideology an overdone misconception. Pouring through the advanced batted-ball metrics wasn’t the sole driver of change, but Holliday said, “I don’t think it hurts. If you’ve got the information, you’d be silly not to at least consider what the information provides.”

Now a Yankee, Holliday has made a concerted effort to avoid the ground, saying, “I figured, if I can get the ball more on the line or in the air and maintain the same exit velocity, obviously that should equal more production.” His average is up 25 points and his slugging up 64—back over .500 for the first time since 2011.

The idea is pervasive even for players like teammate and Yankees rookie slugging sensation Aaron Judge, who says he doesn’t consult the advanced metrics, but is making similar adjustments. Judge has always aimed to hit the ball as hard as he could to centerfield—“I try to knock down the batter’s eye, to be honest,” he said—but worked on a swing path adjustment over the winter to eliminate a flat, across-his-body swing in favor of a focus on lifting his destructive timber upward through the zone.

“Last year and in years past, my swing was kind of like a merry-go-round,” Judge said. When it got in the zone, it came right around.

“My swing now, what I’ve worked on, is more like a Ferris wheel. I want to work back around and up through the baseball.”

Some pitchers welcome the change. Blue Jays starter Marco Estrada has beguiled hitters the past three seasons with his low-velocity, changeup-heavy pitching mix that targets the top of the strike zone and induces neither of the classically safe outcomes: strikeouts and groundouts.

“If you want to try and lift off of me,” he said, “go ahead because it’ll go straight up in the air and eventually become an out.”

One National League scout said some teams “think they can create their own Marco Estrada,” albeit with pitchers who lack the proper command, leading to mistakes up in the zone that often lead to home runs.

“You’re seeing a lot of mistakes get hit out of the ballpark whereas before you were seeing hard line drives and maybe doubles in the gap,” Ellis said. “You’re seeing a lot of non-traditional power hitters, a lot of smaller guys who are able to hit the ball out of the ballpark with regularity, just because of what they’ve been able to do to manipulate their swing.

“The caveat with all this is, it’s a very, very hard swing to make.”

Relatedly, strikeouts are on pace to rise for the 12th straight season, up a staggering 30 percent in that time frame. That’s why cerebral slugger Joey Votto of the Reds recently told the Cincinnati Enquirer, “Everyone tells the good stories, but there’s a lot of shitty stories of guys who are wasting their time trying things.”

Both statistical analysis from FiveThirtyEight and the opinion of evaluators to ESPN concur that the results are a mixed bag. Yankees third baseman Chase Headley made a similar point about how the number of players not adopting new mechanics vastly outweighs those that have success doing so. “It’s pretty difficult to change your swing once you’re in the big leagues,” he said. Instead, Headley argued, such a rise has more to do with team personnel selecting hitters already capable of taking on the en vogue skill set.

“I definitely think there’s more awareness of what’s desirable from an organizational standpoint,” Headley said. “I think teams are trying to get players that maybe hit the ball in the air more, hit the ball with certain trajectories, just like teams are trying to get pitchers with high swing-and-miss stuff.”

The A’s—who else—helped pioneer this trend a few years ago, as noted by Baseball Prospectus after Oakland led the majors in fly balls over the 2012 and 2013 seasons, which served as proof of just how effective an upward swing path is in counteracting predominantly groundball-seeking pitchers. The players themselves were often unwitting. When asked if he considered such data, former A’s outfielder Josh Reddick said, “Not really, no.”

White Sox third baseman Todd Frazier, whose groundball rate has declined precipitously since 2014, said he’s not trying to hit home runs and hasn’t made any concerted effort to elevate the ball more. “That’s just the way my swing goes,” he said.

Not everyone has such self-awareness. Hall of Famer Ted Williams famously endorsed a slight uppercut to the swing. Many other great hitters, however, should be emulated but not listened to.

“You look at their swing and see, ‘Wow, what a beauty,’” independent hitting instructor Doug Latta, whose most prominent client is Dodgers third baseman Justin Turner, a top-10 NL MVP finisher in 2016, said. “But their own description of their swing would be something completely alien to what was actually happening.”

Latta uses terms like “uppercut or Nike swoosh or upswing” to give hitters a visual while explaining that such swings actually a cut more direct path across the strike zone.

“If you take the traditional idea of ‘swing down on the ball’”—Latta chuckled—“and ‘hit ground balls,’ it’s really not even an athletic swing and it leaves massive holes in contact points and really doesn’t allow a hitter hit through a line of the ball,” he said.

Now hitters are understanding and applying those principles with devastating effect.

“The data is definitely supporting a quantum change,” Latta added. “This is a true paradigm shift in how hitting instruction is going to proceed.”