Pitchers can do all kinds of things to change their lives — introducing plyo balls, integrating Trackman, adding kicking modifications — but car preferences tend to be an unchanging reality. Most pitchers fall into one of two buckets: pronator or supinator. Pitchers with very efficient spin (say, 95% and above) on their four-seam fastball belong to the pronator category, while those below 90% are considered supinators. (As a reminder, spin efficiency is a measure of how much spin is “useful;” a fastball thrown with full backspin would have a spin efficiency of 100.) This mechanical shear is usually constant throughout the course. I took 185 pitchers who threw at least 25 fastballs in both 2023 and 2026; over that three-year period, the ur-squared average spin efficiency was 0.65.
In that plot above, you’ll see, as there always are, a few outliers. Another Joe Boyle. Boyle’s story is well known by now, at least in certain social media circles. Over the past three years, Boyle has gone from throwing from an upper arm angle (53 degrees) to a different side arm angle (26 degrees.) The arsenal, in turn, has changed alongside him. This dramatic shift in the slot coincided with his fast spin efficiency dropping from 86% in 2023 to 67% in 2026, another significant drop over that period.
Boyle belongs to that cluster of dots on the left side of the plot that goes from low spin to even low spin performance. Then there is one small dot by itself on the right side of the building. That’s Emerson Hancock.
Hancock, of course, is one of this year’s first sensations. In three starts, he posted a 2.04 ERA and 2.38 FIP, striking out 30.6% of batters in his 17 2/3 innings of work. His last start — Friday, against a hot Astros offense — was the worst yet; He ran into a bullpen in the second and gave up three runs on a bases-clearing double that just missed the third baseman. Still, it was five innings, four hits, three runs, and a display of qualities that fueled this breakout. One-third of his pitches on Friday were sweepers; as recently as two years ago, those games weren’t in his arsenal.
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When it comes to cutting the ball, Hancock is a different case than Boyle. Even in his past, Boyle was a clear supinator; his maximum spin efficiency was 86%. In 2023, Hancock’s fastball was thrown with 99% spin efficiency. Pitchers who are used to swinging the clean ball often have their heaters out, but struggle to throw breaking balls to the side of their gloves — like sweepers — without sacrificing much velocity. To develop a seam-shifted wake that creates a sweeping motion, the pitcher needs to move the gyro spin so that the seams catch the wind. If the ball is thrown with pure backspin or pure topspin, it will not be horizontal like Nolan McLean’s frisbees.
Hancock had a big problem at this stage of his career, back in 2023, when his spin efficiency was at its peak. He was a low-level actor who was feared. Life is tough for the lower-slot pronator. As I wrote about Nathan Eovaldi last year, “the pronation bias blunts their ability to throw breaker-side gloves, and the low arm angle avoids the pronator advantage, killing their fastball.” Eovaldi found a way to make it work; almost no one else can say the same.
Take Hancock’s pitch plot from 2023. What you will see here is the classic pronator triangle, as Mario Delgado Genzor explained it to you. Baseball Prospectus. While supinators have options to expand their arsenal, announcers generally have to work within this triangle, maximizing their abilities to the best of their abilities without significant modification of their pitch shape.
Unless, somehow, you manage to completely change your car preferences. This year, Hancock became a complete pitcher, sharpening the angle on his fastball while adding a glove-side breaking ball with a sweep and lift. Obviously, turning on a better shape to his fastball and a big sweepy breaker was to his advantage; the results in this small sample bear it out. But if it is the case that the efficiency of the spin is often constant and can only be changed by a significant adjustment of the slot, how did Hancock pull this off? Yes, his angle is down 10 degrees, from 23 degrees in 2023 to 13 degrees in 2026. I thought that wouldn’t be the whole explanation. How did Hancock escape the low-slot pronator prison?
This was beyond my pay grade, so I turned to some experts on the subject. I spoke with Spencer Davis, the athletics coach at Southern Virginia University, who suggested that a change in spin efficiency may have had something to do with Hancock’s delivery. He noticed that this year Hancock is reaching more people.
All pitchers talk at some point during their delivery. Those with higher four-seam pitching ability lift earlier in their pitch, while supinators delay that pitch a few milliseconds longer than pronators. As Davis explained to me, a crossbody delivery allows the plantar foot to land faster than a full uninterrupted delivery. When Hancock lands an overhead crossbody, the rotation phase is shortened. His trunk drops quickly in delivery, interrupting his tendency to speak and leading to a voice that doesn’t work very well.
The difference between the stands is subtle but clearly visible. In 2024, for example, he was landing on the left of his back foot:
This season, he landed on the right of his back foot, while starting in the same position on the rubber:
I also spoke with Connor White, Driveline’s director of entertainment. He pointed out that Hancock’s drop in spin efficiency was linked to his changing arm angle, but not in the way I might have thought. In Baseball Savant, the arm angle measurement is taken from one point on the pitcher’s shoulder. Savant’s arm angle paints a rough picture, but as White points out, there are more variables involved in arm angle than just one point. “The arm is not one fixed lump,” he told me. Hancock could be changing his elbow angle, or bending his elbow more, or changing the humerus angle, and none of those factors would affect the arm angle numbers seen in Savant.
Pitching analyst Lance Brozdowski caught up with me on this topic in a video he posted on Friday. (As always, great video. He even singled out Hancock as a perfect example of this phenomenon.) In one segment, Brozdowski offered some explanations for how pitchers like Hancock can dramatically cut spin efficiency. Throwing the cutter too often may inadvertently change the car’s preferences over time; on the intentional side, he reported that teams would change grips and indicators to change the shape of the pitch, or encourage pitchers to use tools like plyo balls or even footballs to change their delivery style.
Which of these applies to Hancock? Some combination of all, or maybe none of the above. It is confidential, and the lack of high-definition motion video precludes any further investigation into the handling changes. What is known are the results: a lower arm position, a newfound ability to cut the ball, and some of the best form Hancock has shown since playing in the majors three years ago. His four-seam fastball once sat in the dreaded “dead zone.” By lowering the angle of his arm and increasing his vertical break, he now achieves a medium height level, at least according to the material models. It doesn’t sound like much, but it may be a necessary condition to carve out an active league career.
As Brozdowski reported, this type of mechanical modification appears to be a strategy of Water’s organization. Hancock is one of four pitchers — Luis Castillo, Logan Gilbert, and Andrés Muñoz are the others — who have had their fastballs slashed the most in 2026. Could this develop into a league trend? There are developmental risks to polluting someone else’s property, Brozdowski said. I’ve also heard from sources that this is a hard pattern to break: Once you get ahead, it’s hard to go back.
For Hancock, the risk seems worth the reward. At the end of last year, he was stuck in an early sixth cleanup, struggling to break into the full rotation. Now he has turned the tables, forcing the Mariners to find a trade for him. Using his spin efficiency, he found a way to belong.
