Misconceptions About Launch Angle by Andrew Perpetua May 11, 2017 There has been so much talk recently about batters increasing their launch angle. You have probably seen dozens of articles from sources all around the internet, some focusing on a reduction in ground ball rates, others on increased home run rates. Some focus on specific average launch angle ranges, claiming this or that average launch angle may be more useful for this or that reason. It is getting confusing, I’m confused. I’m sure you’re confused. Or maybe you’re burned out from all this launch angle talk. Bear with me, I’m going to try to demystify what is going on, and hopefully you can use it to your advantage in the coming weeks while others still struggle. First, exit velocity, generally speaking, means more than launch angle in terms of predicting success. In fact, you can predict batted ball outcomes using exit velocity alone. I have done so in the past, and I could predict how many runs would be scored in any given game with a good deal of accuracy. That’s another topic, though. The key takeaway is this: Exit Velocity trumps angle. Second, exit velocity peaks between -10 and 10 degrees of vertical launch angle for pretty much every batter. I would say every batter, but there is probably an exception. This comes down to physics, mostly. It is determined by the angle of attack on the pitched baseball. Imagine the curve the ball follows between the release point in the pitcher’s hand all the way to the point at which it crosses the plate. As I understand it, on average, that angle is somewhere between 0 and 10 degrees. For breaking balls the angle is steeper, on fastballs it is more shallow, but give or take, averaging everything out, it is between 0 and 10 degrees. Well, that doesn’t really explain why exit velocity peaks, does it? Well, think of it this way: you hit the ball harder if the center of the bat is lined up with the center of the ball. That is obvious enough. Well, if the ball comes in with an angle of 0-10 degrees, then your bat will need to have an angle of 0-10 degrees to achieve maximum exit velocity. So, a launch angle around 0-10 degrees is roughly the default launch angle, give or take. I have a stat for batted balls hit between 0 and 10 degrees. I call it GB. Perhaps I should call it something else? Either way, the name shouldn’t matter, just focus on the meaning. I define GB as batted balls hit between 0 and 10 degrees, and they have the following stat line: Balls Hit Between 0 and 10 degrees BIP H 1B 2B 3B HR AVG OBP SLG BABIP BACON wOBA 49802 23686 21478 2108 100 0 .476 .476 .522 .476 .476 .436 These balls, while you may consider them ground balls or line drives, are perhaps deceptively valuable. The why is clear: they have peak exit velocity. When you hit balls on this angle, generally speaking, you hit the ball very hard. However, the ball is not elevated, so you can’t do an especially large amount of damage with it. Hence, lots of singles. If you hit the ball down the line, you’ll get a double. If you’re lucky, maybe a triple. You can be a productive hitter by maximizing the number of balls you hit in this manner. Christian Yelich, Joey Votto, and Paul Goldschmidt did so last season, each hitting around 19% of their balls on these angles. However, it is preferable to elevate the ball to increase extra base hits and home runs. Bat Speed? Max Exit Velocity? The higher your bat speed, the higher the average exit velocity on batted balls. If you go to xStats.org and sort GB by decreasing exit velocity, you’ll see Stanton ranked first with 105 mph, followed by Pedro Alvarez, Mark Trumbo, Joc Pederson, Justin Upton, Domingo Santana, Josh Donaldson, Jose Bautista, David Ortiz, Ryan Zimmerman, and Cameron Rupp each hovering between 99 and 100 mph. (I am using the 2016 numbers here) These batters have a superior combination of bat speed and hand eye coordination, and it manifests as higher exit velocity. The average exit velocity for balls hit on this angle is 92.9 mph with a standard deviation of 3.3, so each of these guys is in the 98% percentile among batters (z-score = ~2.15; 3.67 for Stanton). Any ball hit above 10 degrees or below -10 degrees is the result of a misaligned bat-ball collision. And as a result, you’re sacrificing exit velocity for launch angle. And the further you misalign, the more velocity you sacrifice. Balls hit between 10 and 19 degrees, which I label LD, have an average exit velocity of 92.8 mph. Down just .1 mph. That’s practically negligible and easy enough to ignore. Balls hit between 19 and 26 degrees, which I label HD, drop to 92.0 mph. Still roughly negligible. Once you reach 26 degrees, the difference begins to show in earnest. Balls hit between 26 and 39 degrees have an average exit velocity of 89.7 mph, and those hit above 39 degrees have an average of 82.6 mph. You can see how exit velocity drops off with launch angle in the charts below. Notice how not only does Stanton have a higher peak velocity around 0-10 degrees, but he also has higher velocities all along the chart. He also has a wider peak velocity, between 0 and 25 degrees or so, prior to exit velocity steeply falling between 25 and 50 degrees. Notice how Stanton can still hit balls above 100 mph around 40 degrees, while DJ LeMahieu cannot hit the ball that hard above 25 degrees or so. What Are The Best Launch Angles? Batted ball value goes up with launch angle, but only to an extent. Everyone seems to have different opinions on where launch angle value peaks. While peaks can vary slightly from guy to guy, you mostly don’t need to think about that. You only need to know one thing: The most valuable batted balls are hit between 19 and 26°. People will tell you different numbers, there seems to be a lot of misinformation and misunderstanding floating around right now. This information is new, I totally get it. I’ve heard people making claims like “balls hit between 15 and 25 degrees are worthless.” That is absolutely wrong. I’ve heard things like “balls hit between 25 and 30 degrees are the best.” That is also incorrect. Let me break this down. A lot of home runs are hit between 25 and 30 degrees. Home Runs By Launch Angle 15-20 20-25 25-30 30-35 35-40 40-45 Total 533 3150 4290 2810 973 200 11956 4.5% 26.3% 35.9% 23.5% 8.1% 1.7% If you want home runs, 94% of home runs are hit between 20 and 40 degrees. 36% of home runs are hit between 25 and 30 degrees. Yes, 25 to 30 degrees is the best angle to hit a home run. That is true. I’m not denying that. The issue is, so many people have conflated *total value* with *home runs*. This clearly isn’t true. Doubles and singles count, too. I charted DJ LeMahieu’s xOBA by launch angle. Take a look at the peak location. I painted the points brown where they are between 19 and 26 degrees, yellow between 25 and 30, and purple when they are between 25 and 26 (ie, in both groups). This chart should do two things. First, you should see that there are far more balls in the brown group than there are in the yellow group. Second, on average, the brown dots are higher than the yellow. Roughly 25% of balls hit between 25 and 30 degrees and 16% of the balls hit between 19 and 26 degrees are home runs. But look at the rest of the outcomes. Percent Of Batted Balls As Hits Angle 1b 2B 3b HR 19-26 16.0% 18.7% 2.1% 15.9% 25-30 8.5% 8.1% 1.7% 24.8% Balls hit between 19 and 26 degrees are twice as likely to be a single, double, or a triple. Yes, 25-30 degrees are almost 1.6 times as likely to be a home run, but that doesn’t make up for the reduced success rates on every other outcome. Just remember this: The most valuable batted balls are hit between 19 and 26°. Balls hit between 19 and 26 degrees have the following stats: Balls Hit Between 19 and 26 degrees BIP H 1B 2B 3B HR AVG OBP SLG BABIP BACON wOBA 47846 25296 7800 9034 1030 7432 .540 .529 1.252 .442 .529 .730 Peak Value Falls Into A Narrow Band. Go back to the prior chart with DJ LeMahieu xOBA and look at how narrow that value band truly is. It is only a very thin slice of the overall picture. You can expand the range out to 10 degrees to the left and 39 degrees on the right. Even still, this is a relatively narrow band of batted balls. Players who want to increase their launch angle to hit for more power need to aim for this range, or risk overshooting and end up hurting their overall production. Note how very high launch angles are very significantly less valuable than very low launch angles. Batters do not want to just increase their average launch angle, because hitting more pop ups obviously isn’t going to help. Furthermore, those lower end batted balls, especially between -5 and 10 degrees, are quite valuable. Rather, batters want to increase balls in this peak area. Between 19 and 26 degrees. Or, more generally, between 10 and 39 degrees. Even better if you can reduce the number of balls hit above 39 degrees. There are batters who have achieved just this. I’m sure you can name one of them right now. Go on. Take a guess. We both know you know who he is. Yup, Yonder Alonso. Can you name anyone else? Mark Reynolds, Francisco Cervelli, Jose Iglesias, Matt Wieters, Manuel Margot, Dee Gordon, Taylor Motter, Tyler Collins, Jonathan Schoop, Ryan Braun, Cesar Hernandez, Corey Seager, Jon Jay, Brett Gardner, Eugenio Suarez. To name a few. All of these guys have increased the number of balls hit between 19 and 26 degrees. Most of them also increased balls hit between 26 and 39 degrees. And most—Collins, Wieters, Reynolds, Suarez, Gardner, Hernandez, McCann, Motter, Gordon, and Schoop—have decreased the number of balls hit above 39 degrees. Batters With Increased HD% Name Δ xAVG Δ xSLG Δ xBABIP Δ xOBA Brett Gardner -.019 .046 -.007 .025 Cesar Hernandez .013 .079 .011 .026 Corey Seager .008 .054 .000 .041 Dee Gordon .013 .025 .014 .011 Eugenio Suarez .077 .161 .056 .110 Francisco Cervelli .020 .110 -.004 .032 James McCann .017 .217 -.060 .114 Jon Jay .014 .007 .024 .035 Jonathan Schoop .038 .037 .031 .016 Jose Iglesias -.032 -.011 -.018 -.048 Manuel Margot -.024 -.028 -.042 .012 Mark Reynolds .020 .093 -.005 .053 Matt Wieters -.019 -.050 -.008 -.005 Ryan Braun -.018 .052 -.014 .032 Taylor Motter .055 .208 .060 .098 Tyler Collins .023 .055 .025 .037 Yonder Alonso -.007 .168 -.037 .077 *Balls Hit Between 19 and 26 degrees Not all of these batters have benefit from increased HD rates. Jose Iglesias and Matt Wieters are two examples of guys who have had an overall net decrease in value this season. However, most of these guys are superior hitters this season, at least in part due to the increased rates of these vital launch angles. I’m not sure how sustainable or predictable these changes are. But they are, at minimum, descriptive, and they highlight the differences you want to look for in batters. Conclusion Merely increased launch angle isn’t a good enough metric. There are many scenarios where increased launch angles can be a very, very bad thing for a batter. Furthermore, you don’t really want to look at average angles on their own, either. It can be deceptive. A guy who hits only pop ups and weak ground balls can have an average angle around 15 degrees, while producing zero value. Instead, look at the key value bands. 19-26 degrees is peak batted ball value. Then you can expand your search to 10 to 39 degrees. Above 39 degrees is effectively worthless, you can consider those pop ups. Below 10 degrees are either low line drives, ground balls or Statcast measurement errors and thusly mostly singles and occasionally doubles. I created a spreadsheet containing much of the data I used in this analysis. The numbers are calculated as follows: 2017 total minus 2016 total. So, for example, if a batter had 20% LD in 2016 and 15% in 2017, then he would be listed with -5% in this table.