Breaking Down the Arsenal of Free Agent Naoyuki Uwasawa

Naoyuki Uwasawa is flying under-the-radar compared to his fellow Japanese counterparts, but could provide teams with quality innings in 2024.

TOKYO, JAPAN - NOVEMBER 10: Naoyuki Uwasawa #15 of Team Japan pitches during the Japan All-Star Series game against the MLB All-Stars at the Tokyo Dome on Saturday, November 10, 2018 in Tokyo, Japan. (Photo by Yuki Taguchi/MLB via Getty Images)

This offseason has featured as exciting of an international free agent class as we have ever seen seen, with more than a combined $400 million expected to be shelled out by MLB teams to sign star Japanese arms Yoshinobu Yamamoto and Shota Imanaga in addition to the $113 million the Giants already committed to Korean outfielder Jung-Hoo Lee.

Those three names alone, plus the excitement of Shohei Ohtani, Cody Bellinger and reigning Cy Young winner Blake Snell can make it easy to gloss over an under-the-radar arm like Japanese right-hander Naoyuki Uwasawa.

In his 11 NPB seasons, the soon-to-be 30-year-old free agent has pitched to a 3.42 ERA in 1,367 1/3 innings with a K-BB ratio that has improved as he gained experience. 2023 was one of Uwasawa’s best campaigns, tossing 170 innings–the second-most of his career–while registering a sub-3.00 ERA for the second time.

Nothing jumps off of the page stuff wise but the right-hander compensates with a great feel for a deep bag of offerings and some unique pitch characteristics. A hitter can see any of a: fastball, splitter, slider, curveball, cutter or changeup with him mixing every pitch but the changeup in at least 10% of the time.

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Only averaging 90.5 mph with his fastball, the finer things become more important. Pitch shape, deception, sequencing, all of the things that made pitchers like: Rich Hill, Aaron Civale and Mike Fiers effective.

Uwasawa’s fastball is far and away his most-used pitch, going to it more than 40% of the time. The pitch plays up compared to fastballs in the same velocity bucket, averaging more than 19 inches of induced vertical break and spin rates above 2,600 RPM.

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The ride and run of the pitch really allows it to get on hitters quickly, picking up whiff at the top of the zone and plenty of weak pop ups. Uwasawa commands his fastball well pouring in strikes at a 68% clip while weaponizing it to all four quadrants.

Against righties, Uwasawa’s fastball often looks like it is starting over the middle of the plate before running in on their hands. He averages around 10 inches of horizontal movement and tracking systems seem to put the fastball all in one bucket since the two versions of his fastball technically have four-seam movement, but the discrepancy between movement profiles in his fastball really make it as if hitters are seeing two different pitches.

Some of his fastballs will feature around 20 inches of IVB and minimal horizontal movement, accentuating the true ride or carry that hitters so frequently swing under. Others will feature around the same vertical movement, but with around 13 inches of horizontal, effectively making it a two-seam variation that can be a front-door weapon to lefties or the aforementioned tie-up pitch for righties.

The fact that the pitch sits in the low 90s at best, somewhat caps the whiff potential it can provide, but bolsters the profile enough that it can stack up with higher-velocity heaters.

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Naoyuki UwasawaUsage: 42%Velo: 90.5Spin: 2640OPS: .660SwStr: 9.6%
Shota ImanagaUsage: 55%Velo: 92Spin: 2510OPS: .705SwStR: 11.2%
Yoshinobu YamamotoUSage: 44%Velo: 95Spin: 2360OPS: .520SWSTR: 8.6%

Generally, a higher release point can negate some of the perceived four-seam carry, but in the unique case of Uwasawa, his over-the-top delivery creates a tunneling headache for hitters as it is difficult to decipher whether the fastball will stay straight with carry, run to his arm side, see the bottom drop out of it (splitter), or if it will cut glove side.


He is particularly adept at matching his release point across his fastballs, splitter and cutter, further aiding the tunneling effect across his wide array of pitches. Interestingly, Uwasawa’s splitter is thrown harder than expected, averaging 86 mph, which is in line with MLB’s average velocity for the pitch.

Generally, the more velocity separation between a fastball and any variation of a changeup, the better the pitch will perform. In the unique case of Uwasawa, the lack of separation seems to play in his favor, picking up higher whiff and chase rates with less offensive output allowed when throwing the splitter above 86 mph.

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It could be that there’s more action on the pitch when thrown harder, or it could be that it matches the fastball appearance more so at a higher velocity out of the hand with hitters geared up for ride towards the top of the zone, helping a tumbling splitter play up.

In terms of shape and velocity, Uwasawa’s splitter shares some similarities to Ian Kennedy and Carlos Hernandez, who held opponents to a combined batting average below .200 with their splitters last season.

If the whiff is not quite there to the degree of Kennedy, Uwasawa should still be able to get plenty of contact on the ground with his split. He has picked up a ground ball rate of 63% since the start of the 2022 season.

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Breaking Balls

Uwasawa will throw both a curveball and a slider that generally have distinctive shapes but can sometimes be tagged interchangeably by tracking systems as he will throw his curveball as slow as 70 mph and as fast as 82 mph, while the slider will range from as 78 mph to 84 mph; he also manipulates the shape of the pitches at times.

The low 70s curveball is a good way to vary looks and slow hitters down and steal early strikes, with the same pitch at 78-80 mph being a more effective swing-and-miss weapon (that’s the case for almost all big, downer curveballs).

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Two of Uwasawa’s different CB looks: 73 mph on left, 80 mph on right.

Though he averaged 75 mph with his curve over the course of the season, he made an adjustment to consistently throw the pitch harder over his final 12 NPB starts, averaging 77 mph with far more pops above 80 mph. Still a couple ticks below Bobby Miller’s curveball, the shape is similar to that of Uwasawa.

Right around the time that Uwasawa’s curveball velocity ticked up, he began to favor the offering over his slider in terms of usage. A traditional slider with about 9 inches of horizontal movement on average and 0 inches of vertical break, Uwasawa goes to the pitch far more frequently to righties.

With his ability to manipulate both pitches while maintaining two distinctive shapes at wide ranges of velocities, hitters will sometimes take late swings at harder curveballs or earlier swings on slower sliders, expecting both pitches not to deviate as far from their average.

The velocity manipulation is helpful as Uwasawa’s slider is about four mph slower than the 85 mph MLB average for starting pitchers. There’s even more correlation between higher velocity and higher whiff with sliders, likely contributing to Uwasawa’s favoring of his curveball in addition to his manipulation of the slider to vary looks.

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Only mixing in his cutter around 10% of the time, the pitch is an asset against right-handed hitters at 86-88 mph. He commands the pitch well, landing it for a strike at a 71% clip in 2023, while holding righties to an OPS below .500 with a ground ball rate just shy of 60%.

Continuing the trend of tunneling here, it seems to be a difficult pitch for same-handed hitters to differentiate from his fastball that either runs in on their hands or rides through the top of the zone. This helps Uwasawa pick up plenty of half-hearted swings and rollovers; it will be pivotal for him to mix in plenty of weak contact if he wants to turn lineups over in the big leagues.

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Uwasawa cutter

Sharing a similar characteristics to Michael Wacha’s cutter–one of his worst performing pitches last year–Uwasawa’s really plays up off of the aforementioned deception as well as his command and sequencing rather than its actual characteristics.

For that reason, it may not be of much use to lefties, who seem to just pick it up earlier and have hammered the pitch pretty well. The effectiveness of his fastball, curveball and splitter negates any concern around his slider and cutter performance against opposite-handed hitters.

Overall Outlook

Though he will be 30 years old by season’s start, he has a big frame and could benefit from a big league strength program to potentially squeeze out an extra tick or two in the velocity department, as has been clocked as high as 95 mph.

While he may not have the margin for error that Yamamoto and Imanaga have given their raw stuff, Uwasawa’s ability to sequence and command a handful of pitches helps his stuff play up. One of my favorite examples of this is the sequence below from his last start of the 2023 season.

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Uwasawa goes to his fastball on the first pitch, which ran back over the outer edge for a strike at 90.5 mph. Then, he goes to his cutter at 88 mph, breaking the opposite direction to freeze the hitter for strike two. The 0-2 pitch is well-located splitter at the bottom of the zone at 83 mph that the hitter catches way out front and rolls foul. He then creates nearly 10 mph of separation–with even more perceived separation–by buzzing 92.4 mph at the top of the zone with more induced vertical break and less horizontal run than the first fastball he threw for strike three.

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Uwasawa four pitch sequence

At bats like that will have to become even more of the norm for Uwasawa stateside, and he has displayed the ability to consistently piece together sequences like this through stretches.

With at least six different pitches and multiple variations of his curveball and slider, there may be a feeling out period as he and his potential big league club gather more information on which of his pitches–and variations of some pitches–will play best against big league hitters.

He is likely to up his splitter usage as splitters in general perform as well as any big league pitch, especially for Japanese pitchers making the move to MLB. The harder, upper 70s curveball played better down the stretch of his 2023 NPB campaign and should similarly be the most effective variation of his breaking ball, especially to lefties.

Right-handed hitters struggled against Uwasawa a bit more last year as every pitch in his arsenal can be an effective weapon against same-handed hitters, while the cutter and slider were hit pretty hard by lefties. The improvement to his curveball and increased use of his splitter should help him maintain decent splits.

Like any international free agent, there’s plenty of unknown with Uwasawa which in this case, could work in his favor. What teams do know is that he can fill up the strike zone and is durable (490.1 IP over last three seasons).

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It pays to be an innings eater these days and two of the St. Louis Cardinals free agent signings are perfect examples. Over the last two seasons, Kyle Gibson has pitched to a 4.88 ERA in 359 2/3 innings of work, yet the Cardinals signed the 36-year-old righty to a $13 million deal for 2024.

Lance Lynn is not much different, limping to a 5.04 ERA in 305 1/3 innings since the start of 2022 and yet the Cardinals shelled out an additional $11 million to sign him for 2024 as well.

The floor may be a bit lower for Uwasawa considering the unknowns, but it’s probably fair to be skeptical as to whether a pair of 36-year-olds in Gibson and Lynn are going to be much better than what we have seen the last two years.

In Uwasawa’s case, the unknown works both ways a bit more. Maybe with his unique arsenal and high-IVB fastball, there’s a No. 4 starter in there. Maybe in an MLB weight program he sees that uptick in velocity that paired with the shape of his heater, could really help him enjoy a jump in the whiff department.

If not, his feel to pitch, ability to vary looks and low-effort delivery should give him a good shot at being a No. 5 starter who can give teams much-needed innings even if its at a mid 4s or slightly higher ERA.

It’s probably fair to say that he likely lands somewhere in the middle, as a back-end starter who can provide flashes of more when he is really in a rhythm and optimizing his arsenal. Regardless, when seeing the price tags across the starting pitching market for established back end arms, the mystery of Uwasawa may just become a bit more intriguing to certain teams.

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