Prep Baseball Report

An Introduction Into Trackman Traits

Mason McRae
PBR Virginia/DC

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Trackman and pitch design are quite complicating. So here's a broad introduction into everything you need to know about trackman data as well as how you can use it to better understand how your pitches work.

Release Speed: Also known as velocity, or RS. Release speed is the most important and self-explanatory metric in pitching. It’s one of the strongest predictors of pitch quality that we know of. It’s not just important on fastballs. We’re beginning to learn through research that the best breaking balls - as well as fastballs, obviously - in terms of swing-and-miss rates tend to have the highest release speeds. The harder you throw, the less time a hitter has to swing. Velocity is also a huge part of vertical approach angle or VAA, which you’ll read about below.

Spin Rate: Unlike most metrics, spin rate is most important in a developmental setting and reported in the number of times the pitched ball would spin per minute, or rpm. Having more spin on your pitch doesn’t mean it’s a better pitch. It represents how much room exists for potential adjustments (aka useful movement) by changing the spin axis or tilt/spin direction. There are about half a dozen types of spin: top spin, raw spin, back spin, true spin, gyro spin, and side spin. For four-seam fastballs, you want more back spin and as little side spin as possible. For most two-seamers, you want side spin and in the rare case you want some gyro spin as well to create a seam-shifted wake (when the tilt of a pitch changes in the last 15 feet of a pitch). For sliders thrown hard, having heavy gyro spin gives it depth while slower thrown sliders tend to want more sweep/ side spin as well as some gyro spin. True curveballs usually want primarily top spin, and very little side spin while more 11-5 curveballs want a combination of side, gyro, and top spin.

So basically, the most important thing to note about spin rate is this: the more you have the better. But having a lot of it on its own won’t make a pitch good as much as turning the raw spin into useful movement would. Remember that spin rate is related to velocity, the harder the pitch the more likely it is that spin increases. You can use Bauer units (formula is spin rate divided by velocity) to adjust for lower velocities in baseline sessions. 

Induced Vertical Movement: Used in short form as IVB, this metric is most important on fastballs for creating rise and on curveballs for creating depth. For sliders and cutters it’s also important. Sliders tend to be closer to zero inches while cutters are generally between five and fifteen inches. Usually fastballs and curveballs with a lot of IVB have higher spin efficiencies as well. While sliders with very little (closer to zero) IVB have very low spin efficiencies. You could also categorize IVB into spin rate as this is part of the “useful movement” you’re looking for. IVB is also a huge part of vertical approach angle.

Horizontal Break: Used in short form as HB. When you think of horizontal movement, you should think of sinkers (or two-seamers), changeups, and sliders. The less HB on a four-seamer or true 12-6 curveball the better. Other ways to think of horizontal break is side spin or movement in a lateral direction.

Release HeightThe only pitch that release height matters for is fastballs. Having a low release height doesn’t make you better, but it certainly helps. Just like having a higher release height doesn’t make your fastball ineffective. The biggest thing to note about release height is that you really can't change it, it's not something you should tweak your delivery to improve. It's best to use in the context of where to throw your fastball. Having a lower release height means (ignoring the context of other metrics like movement/velo) you should throw it up. Having a higher release height typically means you should throw your fastballs down, but once again that is generalizing the two release heights and ignoring velo/movement which you also have to factor in. You also have to factor in the context of a pitchers actual height in this as it benefits shorter pitchers of course. This is another metric that plays a huge part in vertical approach angle.

ExtensionThe distance, reported in feet, from which the pitcher releases the ball relative to the pitching rubber. This is the opposite of release height in the sense that it favors the taller pitchers, but it's also far less important as there is no research to show effective/perceived velocity actually have an effect on how the pitch appears to a hitter.

Vertical Approach Angle: I’ve mentioned vertical approach angle, or VAA three times already. This pitch is basically the metric that takes the three most important things: velocity, movement/release profiles and spits out a metric in degrees. The technical term for VAA is: How steeply up or down the ball enters the zone, reported as the angle in degrees, as the pitch crosses the front of home plate. A negative number means it is sloping downward, while a positive number (rare) means it is sloping upward. Almost all VAA’s are negative, but I tend to write it in a positive number so it’s easier to read/understand.

Some things to note about VAA. Similar to release height, it’s only important for fastballs. There are basically three types of a VAA: flat (good for four-seamers), neutral, and steep (good for two-seamers). Pitchers can be good with somewhat neutral VAA’s, but many pitchers with flat ones tend to generate heavy whiffs (or swing-and-misses). VAA is location dependent. For every 0.665 feet above the strike zone, the average VAA will also decrease (technically it’ll increase as its measured as a negative number) about 0.68 degrees. This means every 0.1 foot above the strike zone, on average, a VAA will decrease around 0.082 degrees. 

Tilt/Spin Axis: Tilt is what we can see through trackman. It's just spin axis converted into clock time and rounded to the nearest 15 minutes. Spin axis is the direction the ball is spinning, reported in degrees of tilt. A pitch thrown at 12:00 has perfect back spin (four-seam fastball). A pitch at 6:00 has perfect top spin (12-6 curveball), while a 3:00/9:00 pitch (typically a cutter or slider) is spinning perfectly from right to left or left to right. The tilt also differs based on the pitcher, for example a left-handed pitcher's fastball has tilts typically from 9:30 to 12:00 while a right-handed pitcher would be from 12:00 to 2:30. Fastballs that end up spinning on the opposite side tend to cut.