Pitch Design: Straightening Out Chris Paddack’s Curveball

San Diego Padres right-hander Chris Paddack had a pretty good first major league season. He struck out 153 hitters in 140.2 innings and posted a 0.98 WHIP with a 3.33 ERA and a 3.95 FIP. Amazingly, he did it with basically two pitches: a four-seam fastball and a changeup. Paddack also has a curveball that he has often tinkered with, but its use never eclipsed 15% in any count. It mainly appeared as the first pitch of the at-bat or when he was ahead in the count. Despite being able to keep hitters under control with two options for most of last season, one of the multiple curveball variations Paddack resorted to works best, both statistically and as an ideal fit with his four-seam and changeup.

Here’s a visual summary of Paddack’s three pitches in an isolated overlay example, which accounts for the typical location of each pitch last season:

Paddack has a well-designed, pure backspinning four-seam fastball with a 12:50 spin direction and nearly 100% spin efficiency. In terms of whiffs, the pitch was best when Paddack kept it high in the zone. When it came to contact, the four-seamer didn’t really have an advantageous location, with the exception of keeping the pitch out of the middle of the strike zone. Paddack held hitters to a .276 wOBA and demonstrated good control of the pitch as evidenced by his 0.18 BB/K-rate.

Paddack’s fading changeup was his best pitch, holding hitters to a .251 wOBA and yielding a 3.67 FIP. Its spin direction is roughly an hour off his four-seamer, which is a good spread for that type of changeup, mainly because of the large amount of movement created between them. Having those two pitches as a mainstay, you’d want as much separation in shape as possible in order to keep hitters honest with their swings. Overall, the pitch worked best for him when he kept it low in or out of the strike zone.

What makes Paddack’s two-pitch success even more intriguing is the amount of release point distance between the four-seamer and changeup. It’s not a huge difference, but definitely noticeable as we can see from the earlier overlay release point freeze-frame:

That brings us to Paddack’s third and scarcely-used option, the curveball. Paddack made a few spin direction changes to the pitch in 2019 with varying results and, interestingly, made no change to his release or mechanics whatsoever.

From late March through June, Paddack’s curveball took on a more 12-6 shape with a small amount of arm-side sweep under a 6:40 spin direction (or about a 20-degree spin axis). In the month of July, Paddack adjusted the average spin direction of the curve to about 7:20 (or 40-degree spin axis), which allowed it to take on a more traditional shape (equal parts sweep and depth). The biggest change to the curve came in August when he again changed the average spin direction, this time from 7:20 to 8:20 (or a 70-degree spin axis), thereby making the pitch more a slurve than a true curveball.

Now that we’ve broken down each pitch, we’ll use the Driveline EDGE tool to look at the shape of Paddack’s 2019 average pitch metrics, of which the fastball and changeup have a minimum standard deviation:

Now let’s take a look at the movement profiles of each type of curveball Paddack threw in 2019. Again, using the EDGE tool, I’ve entered the data for each pitch to demonstrate how they differ, chronologically from left to right. The gyro degree was inferred by using similar profile curveballs, as well as the assumed increase/decrease of orientation based upon the changing spin direction:

Lastly, here are some numbers behind each version of Paddack’s curveball:

The data shows that in terms of contact, the early season curveball was much more effective. Despite seeing his whiff rate increase with each iteration of the pitch, his wOBA ended up almost twice as high as his average earlier in the season.

Regardless of what type of curveball Paddack threw last year — standard, slurve, downer/12-6 — his arm slot lined up seamlessly with his four-seamer’s. This is even more impactful given the fact that Paddack’s early-season curveball creates a mirrored effect with his four-seam spin direction (12:50-6:40). Tighter release points and closer proximity to perfect spin contrast can help keep the pitches bound together at the tunneling point (about 24 feet from home plate). This is dependent upon where they are located in relation to each other, and the type of “hop” (if any) created with the curveball’s shape.

This ability will work best if Paddack keeps his four-seam elevated when he pairs it with the curveball. Since the early-season downer curveball possesses a more arch-like shape, keeping the fastball high will facilitate an effective tunneling combo with a high PlatePreRatio, or the distance ratio between the two pitches at the tunnel point and when they reach home plate.

Here are two examples of how the pitches work with each other both with “proper” and “improper” locations for the four-seam:

As you can see, the pitches are much harder to differentiate when Paddack keeps his four-seamer elevated. It helps create a much more difficult choice for a hitter given the amount of break each pitch exhibits off of each other when traveling to home plate. I’ll use the defensive back analogy where a defender has to account for two receivers: the further apart they are, the larger the margin for error when deciding what side to commit to.

Is a primarily two-pitch approach a good strategy for a starting pitcher? Perhaps if Paddack was more of an Opener, he could get away with it long term. We only have one season of data to go on, but historically, a starting pitcher should have at least three pitches to work with. Could Paddack break that mold and perform at a 3-4 WAR level in the next few years? It’s certainly possible, but seems unlikely.

I don’t think it’s a stretch to assert that Paddack is going to need to throw a third pitch outside of his fastball and changeup more regularly. The early 2019 version of his curveball seems like the most advisable additional pitch. The spin direction of the recommended curveball can create that ideal 180-degree spin mirror with his fastball, and with assistance from the overlapping arm slots, creates a high level of deception that can have overarching positive effects on his entire arsenal.