Flat Fastballs Are Actually Good!....sometimes

Isaac Lippert All or nothing! Strikeouts are at an all time high in both the MLB and NCAA. Increase in velocity however is not the sole reason for this. The continual advancement in technology and the utilization of that technology is at the heart of the pitching dominance we are seeing on a daily basis. The newest metric the pitching world is focused on is “Vertical Approach Angle” (VAA). VAA is one of the many metrics measured by TrackMan. Simply put, VAA is the angle at which the baseball crosses home plate. We measure this in degrees and this angle will always be negative unless the ball is physically rising, which is rare.

Because -7 is mathematically smaller than -3, I will not use “higher” or “lower” when referring to VAA. I will use “flatter” to describe pitches closer to 0 degrees, and “steeper” for pitches further away from 0 degrees. As a general rule with any metric, to be successful you do not want to fall under “average”. Average, by definition, is the meat of a data set. For example, if you throw an average velocity fastball, hitters are more likely to be on time since they see that velocity most often. VAA is no exception to this rule. The three biggest factors in affecting VAA are pitch location, pitch type, and release point. For the purposes of this article, we will talk solely about fastballs. The higher a pitch is located in the zone, the flatter the angle will typically be; the lower the pitch, the steeper the angle will typically be. The most “desirable” angles vastly differ depending on the pitch location. Applying VAA to fastballs, we will look at pitches in the top of the zone and pitches in the bottom of the zone. The following chart, borrowed from Iowa Baseball Managers, displays how fastballs perform in the top of the zone (left) and the bottom of the zone (right) based on VAA.

Pitchers with a flatter VAA will have more success throwing up in the zone. This is because of how hitters perceive the trajectory of a pitch. The brain of a hitter calculates an anticipated trajectory and location. Baseball hitters have a lifelong database in their brain of how a ball moves and where they need to swing to hit it - in simple words, hand eye coordination. If the average VAA is about -5 degrees, hitters have seen this trajectory the most throughout their career. If your fastball is -3 degrees, throwing up in the zone will likely result in hitters whiffing under the ball seeing as how they anticipated it to be lower based on the meat of the curve being closer to -5 degrees. The inverse is true for pitches down in the zone. The more steep the pitch, the more likely it will result in a ground ball or whiff, again because the hitter anticipates the ball to be higher based on an average of -5 degrees. A quick look at the 2 charts tells us that -5.6 degrees (give or take a few tenths) is the least desirable VAA. This is what baseball players might colloquially call a “flat fastball”. This approach to pitching has become popularized with our understanding of spin rate and how spin moves the ball. The quickest, and easiest way to connect these dots is this: high spin rates create more vertical movement leading to success in the top of the zone, while low spin rates cause less vertical movement and have more success in the bottom of the zone. While Spin Rate and Vertical Break are not outdated, VAA is changing how we approach this line of pitch sequencing. Two pitchers with identical velocity and spin rate will differ in VAA based on their release height and extension. This is why pitchers who might have an average vertical break, but throw with a ¾ arm slot can still have a lot of success in the top of the zone. How can you use this information? If you have any access to Rapsodo or Trackman, you can figure out your spin, vertical break and VAA (VAA with Trackman only). You can then use this information to make adjustments and make a game plan in terms of your sequencing. Release point is the most immediate way in which a pitcher can manipulate their VAA. Lower release points will result in flatter pitches, while higher release points will result in steeper pitches. This manipulation can be achieved by adjusting the arm slot, or the extension of the release point. Focus on specific metrics evolves as technology evolves and we have more time to synthesize the data. While these metrics help us optimize every individual pitcher’s unique arsenal, there is still a lot of truth in conventional wisdom. Pitchers should still change speeds, work in and out, and be unpredictable. While VAA is one of the newer metrics pitching coaches are utilizing, there are good resources you can use listed here: Simple Sabermetrics Youtube Video What Goes Into An MLB Draft Model: Vertical Approach Angle Fastball Vertical Approach Angle, Iowa Baseball Managers Examining Pitching Approach Angles