How To Use Statcast Data to Win in Fantasy Baseball
As many of you know, throughout the season, I published a weekly article called “Statcast Trends.” You can find those articles here if you are interested. In each of those articles, I broke down different hitter or pitcher’s statcast trends from Baseball Savant. I tried to explain why each stat discussed in those articles was practical and helpful for Fantasy Baseball analysis.
It is now the offseason, player evaluations for 2021 have begun. Baseball Savant and Fangraphs are both likely a resource you use when evaluating players. You may see stats on those websites that you do not know what they mean. This article has the intention to help you learn more about specific statcast data and other stats and how you can use that data to analyze players for Fantasy Baseball.
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Statcast Data and What It Means
First, I want to preface this by saying, I am still learning. I am not a statcast expert by any means, but I want to share what I have learned with others. I want to show you how I use statcast data to help analyze players for Fantasy Baseball. I hope you find this article helpful.
Baseball Savant Profile
When you first get to a player’s profile on Baseball Savant, you will find a nice picture of the player with the player’s position, whether they bat/throw right or left, the player’s height, weight, and their age. If you move to the right-hand side of the page, you will see MLB Percentile Rankings. This is a list of several different statcast numbers and their percentile rankings among hitters or pitchers.
In the picture above, you can see that Juan Soto ranks exceptionally well in almost every hitting category. When a player ranks well in a category, you will see color and a percentile. If a player ranks highly, that data set will be red. As a player fades toward the 50th percentile, that color will fade red and eventually turn to blue. As you on the other extreme, for instance, Soto’s Outs Above Average, the circle will be very blue.
It is easy to look at a statcast profile like Soto’s full of red and automatically assume that the player is good. The same can be said for a player with a lot of blue in his profile. While it is likely true, it is worth understanding what each stat means and how it correlates to actual stats that matter for Fantasy Baseball.
Average Exit Velocity
Exit Velocity is one of the more simplistic statcast numbers. Essentially, exit velocity is how fast, in miles per hour, a batted ball is hit. Average exit velocity is calculated by dividing the sum of all exit velocity by all batted ball events. Having a high average exit velocity is a skill a player can own. It means a player is hitting the ball hard and has a higher probability of positive results.
Average exit velocity has a high correlation of being descriptive of a player’s wOBA, Home Run percentage, and ISO(Isolated Power = Slugging Percentage minus Batting Average). When projecting a player’s future performance, average exit velocity has the strongest predictive correlation with future wOBA.
Average exit velocity can be useful for Fantasy Baseball when looking at a player’s performance and evaluating whether what they are doing is sustainable. Let’s say a hitter has a .185 batting average over the first month of the season but leads the league in exit velocity. It is possible they have gotten unlucky and could create a good buying opportunity from a Fantasy standpoint. On the flip side, a player off to a hot start, but has just an 85 mph average exit velocity could show a potential decline and be a good selling opportunity.
Average exit velocity is not always the most useful stat. I prefer to take it a step further and look at exit velocity on line drives and fly balls, which is the next statcast number we will discuss.
Exit Velocity(Line Drives/Fly Balls)
Taking exit velocity a step further is looking at a hitter’s average exit velocity on line drives and fly balls. Because average exit velocity includes all batted ball events, bunts, and weakly hit grounders can easily skew it. If you are looking to forecast a hitter’s power, exit velocity on FB/LD is more descriptive and predictive of a player’s power output.
To find this on Baseball Savant, go to the statcast leaderboard and exit velocity and barrels tab. From there, you can sort by EV: FB/LD. You can see in the chart above the leaders from the 2020 season. While Juan Soto had just a 92.1 mph exit velocity, that number jumped to 99.5 mph on fly balls and line drives. This helps explain Soto’s strong ISO(.344) and home run total(13 in 196 plate appearances).
If you are looking to use average exit velocity to evaluate and project a hitter, I recommend using average exit velocity on line drives and fly balls. Studies have proven it is a little more sticky than general exit velocity. It does not matter how hard a player hits the ball if it is drilled into the ground. A player that hits the ball in the air and hits it hard is much more likely to have a better power output. Let’s take a look at another statcast number.
On Soto’s profile that was listed above, you will see hard-hit percentage next to exit velocity. Statcast defines a “hard-hit ball” as one with an exit velocity of 95 mph or higher. A batter’s hard-hit rate is merely showing what percentage of batted balls are hit 95 mph or higher. Studies show that a ball hit with a 95 mph or higher has a much higher probability for a good outcome.
In 2018, balls that were hit 95 mph or higher according to statcast produced a .524 batting average, a .653 wOBA, and a 1.047 slugging percentage. On balls hit below 95 mph, the numbers dropped to just a .219 batting average, a .206 wOBA, and a .259 SLG. That is quite a drastic difference.
I have attached the 2020 hard-hit rate leaderboard above. Typically, platers with a high hard-hit rate perform well. There are several outliers like Evan White, Tyler Naquin, David Bote, and Gregory Polanco. Could that indicate these are sleeper hitters for 2021? It remains to be seen. But, hard-hit rate is a useful stat, as studies have shown, balls hit 95 mph or harder have a high probability of turning into hits.
A barrel is a batted ball with similar hit types in exit velocity and launch angle that has led to a minimum .500 batting average and 1.500 slugging percentage. To be barreled, the batted ball requires an exit velocity of 98 miles per hour. As the exit velocity increases, the launch angle to be classified as a barrel also increases, as you can see in the chart above. The launch angle range grows two-to-three degrees for every one mph increase on the batted ball. Once a batted ball reaches 116 mph exit velocity, a barrel is assigned if the launch angle is between eight and 50 degrees.
Why is this important? In 2019, barreled balls had a .810 batting average! When looking at a hitters profile, a player with a 15 percent barrel rate or higher is considered elite. Anything between ten and 15 percent is considered good, while six to nine percent is average. Of any statcast data, barrel percentage has the strongest descriptive correlation with home run percentage, ISO, and wOBA. Ninety percent of all barreled balls are home runs!
If you are looking to project a player’s future power output, look no further than barrel percentage. It is the strongest predictive statcast measure when forecasting future home runs. Take a look at the barrels per plate appearances percentage leaders from 2020, and you can find some interesting names!
It is no surprise to Fernando Tatis, Corey Seager, and Juan Soto atop the leaderboard. Eloy Jimenez fourth makes me further believe a 2021 breakout is possible. Teoscar Hernandez being fifth on the list, helps solidify his breakout. The Statcast leaderboard is extremely useful when looking at players with breakout potential by looking at the barrels leaders.
Launch angle represents the vertical angle that a batted ball leaves a player’s bat. A player’s average launch angle is calculated by dividing the sum of all launch angles by all batted balls. The launch angle revolution has taken the league by storm, with players trying to achieve optimal launch angle.
Average launch angle is not an excellent tool for evaluating a hitter. I think it can be more valuable when discussing pitchers, but we will get to that next week. A hitter’s launch angle can tell us about the tendencies of a hitter, though. If the player has a high launch angle, they may be more of a fly ball hitter. On the flip side, if a player has a low launch angle, like Yandy Diaz, they are likely to be a groundball heavy hitter. Diaz had an unusual, negative 7.9-degree launch angle, which led to a 66 percent ground ball rate. For those wondering, a negative launch angle is never good!
One reason average launch angle is not always a telling stat is that it just an average. A player could have a high ground ball and fly ball percentage, which leads to a solid launch angle. Take Teoscar Hernandez, for instance. A player who enjoyed a breakout 2020 season had identical launch angles in 2019 and 2020 at 15.3 degrees.
Look at his charts, though. 2019 is on the left, while 2020 is on the right. While the average launch angle was the same, you can see Hernandez’s spread of batted balls was much tighter. For that reason, he increased his sweet-spot percentage by over ten percent and had an improved “launch angle tightness.” All of that to say, average launch angle is not always the best stat to use when analyzing a hitter. It is essential to look deeper and beyond just the average launch angle. The next stat I will discuss is one that I think is more useful than a hitter’s average launch angle.
Sweet Spot Percentage
The “Sweet spot” is classified as a batted ball that is hit between an eight and 32-degree launch angle. A hitter’s sweet spot percentage is how often that player produces a batted ball event with a launch angle between that eight and 32-degree threshold. Sweet spot percentage is useful but in the right context.
Ben Gamel was the league leader of sweet spot percentage at 49.3 percent. Gamel also had an average exit velocity of 87.9 mph and a hard-hit rate of 32 percent. So while he hit the ball in the sweet spot nearly half of the time, he did not hit the ball hard enough to make much of a difference in production.
Second on the list is Freddie Freeman, who hit the ball in the sweet spot 49.2 percent of the time and had a hard-hit rate of 54.2 percent. Also, Freeman had an average exit velocity of 92.4 mph with a 95.7 mph exit velocity on line drives and fly balls. Sweet spot percentage becomes useful when a player has a high sweet spot percentage and a high exit velocity on those batted balls.
As you can see in the chart above, batted balls in the sweet spot had a higher wOBA. But look at the jump when you factor in hard-hit balls. The moral of the story is, players who have an increased sweet spot percentage and hard-hit rate typically perform well. Here is a chart of players with a sweet spot percentage and a hard-hit rate of over 40 percent. This list is descriptive of how the hitter performed in 2020 but could be a predictive indicator of future success.
I hope you have found this article useful. Statcast data can be beneficial when evaluating a player’s performance a projecting their future. It is also possible to overuse statcast data. It is not an “end-all-be-all.” It is just another tool in the toolshed that helps us with player analysis.
If you have any questions, feel free to reach out on Twitter @RotoClegg, and I will always be happy to help you with any understanding of statcast data or answer any Fantasy Baseball questions. Check back next week as we look at how to use statcast data for pitchers. But for now, be sure to check out Eric Cross’s updated Top 500 Dynasty Ranks. If you play in a dynasty league, you need to read check this out!
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