August 3, 2016

The Toolshed

The Curveball

by James Fisher

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In today’s installment of The Toolshed we will tackle one of the more difficult pitches to throw consistently, the curveball. It has been blessed with many a moniker over the years: “Uncle Charlie,” “Yakker,” and “The Deuce” among them. The curveball is often easier to throw for pitchers with higher arm slots—true three-quarters and above—because it’s easier to position the wrist and keep the fingers on top of the ball where they need to be. Most pitchers start their grip with the middle finger on the seam, while the thumb either extends or curls under, on the opposite seam. Others, with increasing frequency, prefer the knuckle, or “spike,” curveball grip. In this iteration, the index finger is tucked back and the first knuckle is used to grip the baseball. The delivery should be the same as that for a fastball, except for the karate chop-like motion at release that imparts topspin on the baseball.

The 12-to-6 curveball is the most iconic, but the shape can vary to include 11-to-5 and even 10-to-4 trajectories. But as the angle lowers, the pitch will start to run into a slider shape and get “slurvy,” with more horizontal break than vertical depth. Velocity-wise, the typical curveball will be in the low-70’s to low-80’s, but it will generally be at its best at the higher end of that velocity range, because with velocity comes a sharper, tighter break. The less velocity the pitch has, the greater the likelihood its rotation will loosen and cause the pitch to hang up in the zone.

Now that we have covered the basics of how it’s thrown and what it looks like, let’s tackle the grading of the curveball.

The 60: Jameson Taillon

Having just received his call to the big leagues, Taillon is an excellent place to start. According to our own Adam Hayes in his Eyewitness Report, the shape wavers between a 12-6 offering that features true drop-off-the-table action and an 11-5 that has a little more two-plane action. The gif below is the 11-5 variety.

Video courtesy MLB

The 50: Jake Thompson

Thompson’s curveball is more of the 11-5 variety, and it features more depth than lateral break. The pitch wavers in its consistency because he gets around on the ball instead of staying on top and letting gravity do the work. In this gif we can also see that he is throwing with a knuckle curve grip.

Video courtesy MiLB

The 40: Andrew Moore

Moore throws the 12-6 variety of curveball from a borderline overhand release. According to Wilson Karaman’s Eyewitness Report, the pitch ‘’has a round shape that tightens up at higher velocities’’ and “lacks consistent depth.’’ He also noted that hitters saw it out of his hand relatively well the second time through the order. There’s a lack of feel and tightness to the pitch, with less consistently tight spin.

Video courtesy MiLB

Now that we’ve identified what the standard grade curve of a useful curveball looks like, let’s close with some context and take a look at one of the best hooks of all time, belonging to Sandy Koufax.

Video courtesy MLB

In the next installment we will take a look at the cousin of the curveball, the slider.

James Fisher is an author of Baseball Prospectus. 
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