Meet the Man Who Couldn’t Miss a Bat

Kamil Krzaczynski-Imagn Images

You might not know the name Jack Kochanowicz. It’s a tricky name to pronounce, after all. (Ko-hawn-o-witz). He also made his major league debut on the very day in July when the Angels’ playoff odds hit 0.0%. So if this is your first Jack Kochanowicz experience, just know that he’s capable of doing stuff like this:

Another thing you should know: No pitcher last season missed fewer bats. Out of 351 pitchers with at least 50 innings pitched in the 2024 season, Kochanowicz’s 9.4% strikeout rate ranked 351st.

I’ve been fascinated by Kochanowicz because of this contradiction. He can ramp his heater up to 99 mph, and yet his K/9 started with a three. What gives?

In the interests of setting up this article, I’ve left out some key pieces of information. That fastball Kochanowicz blew past Dustin Harris? It was one of just 53 four-seamers he threw last season, comprising just 6% of his total pitches.

In lieu of the four-seamer, Kochanowicz threw almost exclusively sinkers. It didn’t matter whether he was facing a lefty or a righty, pitching early or deep in counts – in nearly every context, the 6-foot-7 right-hander picked the same pitch. A full 72% of his pitches were sinkers. No starting pitcher threw a single pitch that frequently. Nobody was even really that close — Justin Steele, at 59% usage of the four-seamer, came in second place. (And even Steele would tell you that his fastball is actually more like two pitches.)

To be fair, it’s not hard to see why Kochanowicz likes his sinker so much. It sits at 96 mph, averaging about 16 inches of horizontal break and less than three inches of induced vertical break. It’s what you’d classify as a turbo or bowling ball sinker. After debuting, he was the king of throwing these types of pitches, explaining most of why Kochanowicz sat in the 94th percentile of pitchers in groundball rate.

Turbo Sinkers
Pitcher Pitch Type Pitches
Jack Kochanowicz Sinker 289
Yennier Cano Sinker 186
Ryan Walker Sinker 120
Brayan Bello Sinker 115
Jhoan Duran Splinker 102
Zach Pop Sinker 97
José Soriano Sinker 74
Jake Bird Sinker 70
Chris Roycroft Sinker 68
Justin Lawrence Sinker 67
SOURCE: Baseball Savant
From 7/11/24 onward. Pitches thrown above 95 mph with fewer than three inches of induced vertical break.

Because Kochanowicz is so tall and doesn’t extend particularly far down the mound, he throws his sinker with one of the league’s steepest vertical approach angles. As Alex Chamberlain showed, these steep VAAs maximize sinker effectiveness.

In a vacuum, it’s a great pitch. But throw any pitch at that frequency, and hitters will eventually catch on. As Stephen Sutton-Brown showed in his article on Baseball Prospectus’ new arsenal metrics last week, hitters are much less likely to whiff after they’ve seen a pitch twice. That effect is mitigated if pitchers wield an above-average “Surprise Factor,” which looks at the unexpectedness of a pitch given the distribution of all possible movements in a pitcher’s arsenal. Kochanowicz, as you might surmise, does not excel in the element of Surprise — he ranked in the 13th percentile in Pitch Type Probability and the 22nd percentile in Surprise Factor, according to BP’s metrics. Excluding relief pitchers, Kochanowicz would likely ranked near the bottom in both of these metrics.

So part of Kochanowicz’s lack of whiffs can be linked to the simplicity of his approach. But there’s also something about the pitch itself, independent of Kochanowicz’s usage patterns. Hitters swung and missed at just 13.9% of sinkers in the 2024 season, far fewer than any other pitch type.

Why do batters make contact so frequently with sinkers? It might be helpful to start with this plot. Here, I’ve bucketed every single four-seam fastball and sinker thrown in the 2023 and 2024 seasons into horizontal and vertical movement pairs, then calculated the whiff rate for each pair. (I removed any pair with fewer than 500 swings in the sample, which explains the blank parts on the lower left part of the plot.)

As the plot shows, whiff rates are highest when fastballs are thrown with the most ride. As vertical movement decreases, whiff rates decrease in a relatively linear fashion. The relationship between horizontal movement and whiffs isn’t as clear, but to my eye, it almost appears that more arm-side run — a quality associated with most sinkers — actually leads to fewer whiffs.

To measure this with greater rigor, I fit a logistic regression model to predict whiffs on this same dataset of all four-seamers and sinkers from the last two seasons. Perhaps because I didn’t use a sophisticated machine learning library, the model wasn’t amazing at prediction — it predicted “no whiff” at about 85% accuracy and “whiff” at roughly 40% accuracy — but the regression allowed for more interpretability. And in this case, I wanted to specifically understand the relationship between horizontal movement and whiffs for fastballs.

The effect size is small, but I was surprised at the direction of the result. According to the model, each additional inch of horizontal movement (pfx_x, on the table above) decreases the likelihood of a swing-and-miss.

A sinker like that of Kochanowicz is, according to this model, essentially optimized for running into bats. This didn’t make intuitive sense to me. Kochanowicz’s sinker is moving just as fast as a Blake Snell four-seamer with wicked outlier movement. Why does one type of outlier movement — gravity-defying backspin — lead to tons of swing-and-miss, while the other leads to the worst strikeout rate in the league?

I can offer two possible explanations here. One is best articulated by Alex Chamberlain in his primer on horizontal approach angle, so I’ll just quote him at length:

“A hitter’s swing has a much wider margin of error laterally than it does vertically. Horizontally, an inch off the barrel probably still results in contact, just inferior contact. In fact, with a miss of several inches, a hitter can still foul one off or even luck into a base hit. On the other hand, a one-inch miss vertically is, at best, a foul tip; at worse, it’s a straight-up whiff.”

But not all vertical misses are created equally. Missing below the ball leads to whiffs, while missing above the ball can still lead to contact. This much, I think, is tied to the nature of the swing path.

As I tend to do when I’m stumped by a hitting question, I DM’d Esteban Rivera, asking why nasty sinkers run into more bats than backspinning four-seamers. Esteban wrote that most swings have a positive attack angle, meaning that they are angled slightly upward as they pass through the strike zone. These positive attack angle swings, he said, have “more points in space (and time) where the horizontal + vertical bat angles match the planes of sinkers.” Imagine a Kochanowicz sinker boring into the zone, and imagine a swing with a slightly upward swing path moving to meet it there. There are just more points in time when the two paths can intersect compared to a four-seamer from a super low release point.

Desperate to see this phenomenon in practice, I sent a Skeet into the ether, asking for any helpful GIFs. Tom Tango, MLB’s senior data architect, replied with some sweet behind-the-scenes visualizations. The first captured a Bryce Harper whiff on a Bryan Woo fastball at the top of the zone, which I figured would provide a good example of the latter example. Look at how the flat fastball leaves a tiny window for contact:

Does this work for you?

Tangotiger (@tangotiger.com) 2025-01-28T20:34:58.994Z

And here’s Harper walloping a Tarik Skubal sinker, the plane of his swing lining up nearly perfectly with the steeper approach angle:

And the other Harper

Tangotiger (@tangotiger.com) 2025-01-28T20:54:23.972Z

The various projection systems see Kochanowicz boosting his strikeout rate in 2025. Some of that is just pure regression, which I can get behind. Beyond regression, though, I believe he has the skill set to miss more bats. That likely starts with throwing his four-seam fastball with greater frequency from the jump. If this tweet from a pitching lab he visited earlier this season is any indication, it appears that the further development of this pitch has been a focus of his offseason.

That same tweet also referred to “clean[ing] up both breakers,” which was a surprise to me — Savant lists Kochanowicz as throwing just one breaking ball. A look at his pitch plot, however, does show that his “curveball” assumed a variety of shapes, some moving in a gyro-y fashion, some looking sweepier, but in any case showing no clear separation. (Look at the variety of movement patterns for the blue dots on the left side of the plot.)

If Kochanowicz was indeed throwing two separate breaking balls, “cleaning them up” — or dividing them into distinct shapes — would be a great start. But he can clearly spin the ball, meaning there is a path to throwing a swing-and-miss breaker to right-handed hitters. Take this curveball he threw to Spencer Torkelson — 87 mph with negative induced vertical break and eight inches of sweep would almost certainly grade out as a plus pitch by a stuff model:

Even as the whiffs inevitably trend up, it’s hard to imagine Kochanowicz straying too far from a pitch that powered a totally respectable rookie campaign. Selfishly, I hope he stays on the extremes, pushing the limits of how far a single pitch can take a starting pitcher.





Michael Rosen is a transportation researcher and the author of pitchplots.substack.com. He can be found on Twitter at @bymichaelrosen.

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JRMayneMember since 2016
14 days ago

Fun article!

WilliamMember since 2020
14 days ago
Reply to  JRMayne

I agree. I learned a lot about Jack’s arsenal, as well as finding out that I’ve been pronouncing his last name incorrectly.