Baseball Smarter: Why Baseball Digs The Fly Ball

[Matthew Creally]

Image courtesy of © Raymond Carlin III-Imagn Images

Why does putting the ball in the air matter? Anyone who has been watching baseball consistently for at least a decade or so knows that lifting the ball is a phenomenon that captured the attention of every team in the major leagues throughout the 2010s. The trend was so far-reaching that the Washington Post put out an article in 2017, coining it the "Launch Angle Revolution". Unfortunately, this also coincided with a period where MLB grew quite dissatisfied with the entertainment quality of their on-field product, which led to the introduction of bigger bases and a ban on extreme defensive shifts in the early 2020s. This overlap has resulted in the very concept of a flyball-centric approach being discussed in negative connotation by some of the game's more traditional fans. So, why did baseball become obsessed with flyballs in the first place?

It started around the time that front offices got their hands on data points such as launch angle that have become commonplace today thanks to Statcast. By tracking the angle of every batted ball, MLB was now able to explicitly define batted ball types instead of qualifying them visually, which isn't always the easiest thing to do: Differentiating between groundballs and line drives, line drives and flyballs, and flyballs and popups cannot be done with complete precision 100% of the time. All anyone needs to do to understand why flyballs became highly valued is to look at league-wide results by batted ball type. Using the 2025 regular season as an example, hitters were wildly productive on flyballs:

Type	AVG	SLG
Groundball	0.249	0.272
Line Drive	0.628	0.870
Flyball	0.261	0.805
Popup	0.013	0.014

Already, it's time to make a very important distinction. You'll notice that line drives produced a higher batting average and slugging percentage at the league level. Why didn't everyone try to hit line drives instead? Technically, line drives are the most optimal batted ball type for hits in general, but flyballs are the only batted ball type that generates outsized amounts of slug. Slugging percentage on flyballs was only 65 points lower than line drives despite batting average being nearly 400 points lower. That's because a decent amount of flyballs end up as home runs. You can't hit homers without hitting flyballs. The logic is sound: Home runs are the most valuable type of hit in baseball. Flyballs lead to home runs. Hit more flyballs. This conventional idea long predates the advent of launch angle, though. To steal a quote from that Washington Post piece by the great Ted Williams: 

Quote

“The ‘level swing’ has always been advocated. I used to believe it, and I used to say the same thing. But the ideal swing is not level, and it’s not down. . . if you get the ball into the air with power, you have the gift to produce the most important hit in baseball — the home run.” - Ted Williams

Only, it isn't that simple. On top of being hit in the air, batted balls need to be hit at a high velocity in order to end up as home runs. A more precise way to define the Launch Angle Revolution would be to note that hitters across the league began hitting hard fly balls. This is the concept behind the popular Statcast metric called Barrels, which are batted balls with a combination of exit velocity and launch angle likely to result in an extra-base hit. The threshold changes dynamically; for example, a batted ball hit at 99 MPH is only likely to be an extra base hit if it comes off the bat at a small handful of launch angles. A 112-MPH hit, meanwhile, leaves a little more room for error on the launch angle side of things if extra base hits are the target.

Within all this lies a key caveat: The direction of a flyball heavily impacts the result it achieves. Soon after, teams discovered that pulled flyballs frequently outperform their expected results based on exit velocity and launch angle. Why? The answer has also been intuitive since the dawn of baseball: The wall isn't as far away on the pull side as it is in center field! Observe the results from 2025:

Direction	AVG - xAVG	SLG - xSLG
Pull	0.135	0.500
Center	-0.088	-0.381
Opposite	0.010	-0.032

Pulling flyballs, through timing of the swing and depth of contact point relative to home plate, is a repeatable skill. Cal Raleigh hit 60 home runs last year. He has a ton of raw power, as his barrel rate was in the 99th percentile among MLB hitters, but he also pulled the ball in the air more than almost anyone in the league (33.8% of his batted balls were pulled in the air according to Baseball Savant). Isaac Paredes has hit the 20-homer mark 3 times in his career despite never posting above-average exit velocities because he pulls flyballs all the time.

We've established that hitting the ball in the air matters because it's the only way to slug, the only way to consistently record the most pivotal types of hits. Pulling flyballs is also important because it allows hitters to achieve higher home run totals than we'd expect based on their raw power. Why doesn't everybody do at least one of these things all the time? It's because not everyone can hit home runs, and while they're important, they aren't a prerequisite to being a good hitter. Take Luis Arraez as an example. He has 36 career home runs, and he's been around for eight seasons and counting, yet he's been productive for almost that entire timespan because he never swings and misses, which means he puts the ball in play a lot, and a good chunk of those balls in play are line drives. That's how you get a career batting average of .317. No, he isn't as valuable as your prototypical elite slugger, and he doesn't hit as many doubles as he used to, so his overall production has tapered off in recent years, but high-contact, line-drive hitters are still a constant threat even if there aren't a lot of them.

What if you're someone who hits a ton of grounders? That can sometimes work too. Brewers outfielder Sal Frelick has started 2026 on the wrong foot, but last year, he hit the ball on the ground more than most hitters in the league, and he only had a 4th-percentile hard hit rate. He still hit .288 and was a positive contributor for the team that wound up with the best record in baseball. How? His foot speed was a primary factor. Frelick's sprint speed was in the 87th percentile, meaning he's fast enough to leg out infield singles, and he also stole 19 bases. He's listed at 5'9" and 191 lbs; like Arraez, he isn't someone who would benefit from hitting the ball in the air all the time because he doesn't have the physical stature of an Aaron Judge or a Shohei Ohtani that would give him clear home run potential. For many hitters, groundballs are bad because they don't leave the infield, they're an automatic out when they're hit hard right at somebody, and they can even lead to multiple outs with runners on base. For someone like Frelick, who doesn't elevate but doesn't hit it hard either and has the speed to occasionally cause chaos on the bases, the path of least resistance is keeping the ball down.

The 2025 Brewers are a great team-level example of the exception to the flyball rule. By runs per game, they were a top-3 offense in the league despite ranking 29th in flyball rate. Their lineup was full of hitters that were productive despite low launch angles (Christian Yelich, William Contreras, Brice Turang, Sal Frelick) because they're either fast, have an advanced all-fields approach, or both. Maybe this offensive philosophy isn't the best fit for a team with World Series aspirations, as Milwaukee's bats went ice-cold in the NLCS, but they zigged when others zagged, and it got them farther than most were expecting.

While it isn't an absolute black-and-white case, intuitive logic, as well as league-wide results, provide a convincing case in favor of lifting the ball and emphasizing hard-hit flyballs as the most sustainable blueprint for long-term offensive success.

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