Musings at the Intersection of Launch Angle Consistency and Hard-Hit Rate

If you follow the work of Alex Chamberlain at all, you’ve heard of the value of launch angle consistency. I’m not going to recapitulate his body of work on the subject, but briefly: hitters with tighter launch angle distributions routinely run higher BABIPs, and you can think of launch angle consistency as roughly a proxy for “hit tool.”

Most of this comes down to avoiding terrible batted ball outcomes. The two worst things you can do when you put the ball in play are to hit it straight down or straight up. Given that balls are, on average, hit mostly forward and with a tiny bit of loft — breaking news, I know — launch angle consistency is a great proxy for how often you avoid those, because the more -80s and +80s you put in your sample of mostly 10s and 20s, the higher the standard deviation gets.

One thing I’ve often wondered is whether this idea of consistency holds up for subsets of batted balls. Intuitively, it seems like it might. Take hard-hit balls, for example. If you’re hitting the ball 95 mph or harder, you really don’t want to squander it by hitting the ball on the ground or straight into the air. The distribution peaks at 30 degrees, but anything between 10 and 35 is a solid outcome.

With this in mind, I decided to look for batters who grouped their hard-hit balls most tightly. Having a narrow distribution seems like a great way to maximize good outcomes. Which player, you ask, has the tightest launch angle consistency (I’m just using standard deviation here) on hard-hit balls? I’m glad you asked — it’s Dee Strange-Gordon.

Not what you expected? It certainly wasn’t what I expected. Strange-Gordon is extremely consistent when he makes solid contact. There’s just one problem: he consistently hits it into the ground. His average launch angle on his hard-hit balls was just 7.6 degrees (in 2019 and 2020 combined, to get a reasonable sample size). A full 40% of them left his bat at 5 degrees or lower.

In fact, Strange-Gordon was in the 27th percentile in terms of production on hard-hit balls. He also didn’t hit many of them, which is neither here nor there, but clearly launch angle tightness is insufficient to explain how much value hitters get out of their hard-hit balls. There’s basically no correlation between raw standard deviation and production. Angle matters too.

What if we instead looked at what percentage of batted balls were within a given range of launch angles? It sounds a bit like sweet spot percentage, and it kind of is, but if you’re looking for someone who can repeat a swing that hits the ball hard and in the air, seeing how frequently someone’s hardest-hit balls are in the air sounds like a good start.

I decided to define it like so: if a ball was hit between 10 and 35 degrees into the air, I called that a good outcome. Which batters had the highest percentage of good outcomes on their hard-hit balls? Take a look:

Even though this list isn’t an exhaustive list of the best hitters in baseball, it’s starting to get at something interesting. Omar Narváez isn’t a great hitter, but he’s always punched above his weight when it comes to hard-hit rate. The same is true for Fowler — he doesn’t hit the ball hard all that frequently, and of late he hasn’t even had the walk and strikeout numbers to make up for it, but he managed a reputable ISO despite a hard-hit rate 10 percentage points below league average.

Overall, there’s a meaningful correlation between production on hard-hit balls and how often hitters keep them in a valuable range of angles (0.15 r-squared with wOBA and 0.3 r-squared with xwOBA). Again, this isn’t a surprising finding, but it’s helpful for understanding why some batters get more out of their contact than others.

That’s just in year one, though. The first thing I wondered after finding this out was whether this “skill” carries over from one year to the next. In other words, do hitters who hit their hardest balls in the air one year continue to do so in the future? To check, I looked at the same cohort of hitters in 2018 and 2019 — all batters with at least 50 hard-hit balls in both years.

Bad news: they’re not actually all that strongly correlated. More specifically, there was a 51% correlation between one year and the next. That’s low in the hierarchy of repeatable skills — right in line with something like batting average for hitters or home run rate for pitchers. That doesn’t mean it’s a worthless stat, but it does mean that you shouldn’t look at what a hitter does in terms of elevating his hard contact one year and take it as gospel.

That said — and boy, this article includes a bunch of caveats — in the long run, hitters pretty clearly demonstrate this ability. Brandon Belt and Freddie Freeman are the top two hitters at putting the ball into play dangerously when they hit it hard, using every batted ball since the start of the 2015 season. Matt Carpenter and Nick Castellanos are third and fourth. Mike Trout, Joey Votto, and Alex Bregman are in the top 15. Good hitters really do seem better at this skill.

The very bottom of the list? Old friend Dee Strange-Gordon. Eric Hosmer is in the bottom five as well — makes sense, given his old groundballing ways. Javier Báez is in the bottom 10 — he hits the ball hard frequently, but it’s hardly shocking to learn that he doesn’t always hit it pure given his free-swinging ways.

This thread will require further untangling, but I’m glad that there are at least a few takeaways from an initial study. Launch angle tightness doesn’t work well when considering only hard-hit balls. Why not? I can’t prove it, but I have a strong hunch that it has to do with why launch angle tightness works in the first place. Because of the nature of standard deviation, outliers have an outsize effect. What is launch angle tightness measuring? A hitter’s ability to avoid outliers, namely pop-ups and balls that batters top straight down.

Switch to only hard-hit balls, and a lot of those outliers disappear. As dynamic hard hit rate demonstrates, it’s hard to hit balls that hard at that crazy of an angle. In other words, looking only at hard-hit balls removes some outliers, and given that launch angle standard deviation is a measurement of avoiding outliers, it loses predictive power.

My made up statistic, hard-hit sweet spot percentage, correlates well with line drive rate. That also makes sense: the more squarely you hit the ball, the more likely you are to hit it hard, and also the more likely you are to hit a line drive. Since 2015, 51.2% of all line drives have been hit at 95 mph or harder, as compared to 29.1% for all other batted balls.

In the end, none of this tells us anything we didn’t already know intuitively. It’s bad to hit the ball straight up or straight down, it’s good to hit line drives, and it’s especially good to hit hard line drives. Can I put these into a single number that tells you what you need to know about a hitter? Absolutely not. Eventually, that will start to be frustrating. For now, though, I’m still calibrating how to think about all of this together. Launch angle dispersion is a great top-level metric. One day, I hope I’ll find an exciting way to tie it together with other indicators and find something new.