Haruto Inoue Isn't Just "Recovering"—He's Reinstalling His Pitching OS

—Reading the data of the Giants' left-hander in 2026

(Posted during the 5/15 appearance, so 5/15 stats are not included)

In 2026, Haruto Inoue looks good enough even just looking at surface-level stats.

5 games, 5 starts, 29 2/3 innings, 2.12 ERA. 33 strikeouts, 7 walks, 1.01 WHIP. K% is 28.0%, BB% is 5.9%, K-BB% is 22.0%.

However, the point of this article isn't just to say "he's a good pitcher because his ERA is in the low 2s."

In the NPB Scholar individual player data, Inoue's 2026 is showing up quite strongly. Overall Stuff+ is 103.4, and Location+ is 106.6. The strength of the pitches themselves is above average, but the evaluation of where he throws them is even higher. Furthermore, PRV is +4.0, xERA is 2.57, FIP is 2.25, and xFIP is 2.09. In other words, it's not just that his ERA is good; his "pitch quality," "location," and "skill estimation" are all trending upward simultaneously.

The interesting thing about Inoue is that he didn't just break out as a first-team starter in 2024, hit a wall in 2025, and return as the same pitcher in 2026. He has returned by changing the very way he constructs his pitching.

In conclusion, the 2026 Inoue is transforming from a "lefty who wins with fastballs and sliders" to a "lefty who breaks the batter's swing angle while staying in the fastball velocity band." While he looks like a power lefty, he also possesses the elements and potential of a finesse lefty.

This isn't just a simple increase in velocity.

From the quality of the fastball and the development of the forkball as a finishing pitch to the increase in two-seamers and cutters, and even how he uses the zone, a very consistent design change is visible.

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1. In 2024, Inoue had already found one "answer"

Haruto Inoue's breakout in the first team was in 2024.

He pitched 101 innings with a 2.76 ERA. His FIP was also in the mid-2s, and his performance was sufficiently excellent. K% was 24.0%, BB% was 6.5%, and K-BB% was 17.4%. At that point, these were quite strong numbers for a young left-handed starter.

What supported Inoue that year were his fastball and slider.

Looking at pitch value by type, in 2024, the fastball was +1.5, the two-seamer was +3.1, and the slider was +8.2. The contribution of the slider was particularly large. Its usage rate was 26.9%, making it the second most used pitch after the fastball at 44.3%.

In other words, the 2024 Inoue was a pitcher who pushed with the fastball and finished with the slider.

This is a very easy-to-understand success pattern. Having an above-average fastball as a lefty and being able to get swings-and-misses and weak contact with a slider from there was a more than sufficient weapon configuration for a young pitcher to enter the rotation.

But a problem occurred in 2025.

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1. The 2025 slowdown was less about "pitch quality dropping" and more about "batters creating angles"

In 2025, Inoue pitched 107 innings. In terms of workload, it actually increased from 101 innings in 2024.

However, the quality dropped.

ERA was 3.70, FIP was 3.58. Home runs allowed jumped from 5 in 2024 to 15. K% was 22.1% and BB% was 4.2%, so the balance of strikeouts and walks itself wasn't that bad. In fact, walks decreased.

So, what got worse?

The answer is the batted balls.

The ground ball rate in 2024 was 50.7%. In 2025, it was 40.9%. Conversely, the fly ball rate rose from 39.3% to 47.2%. HR/FB also jumped from 4.7% to 10.0%.

In other words, in 2025, batters were creating launch angles against Inoue.

The average fastball velocity had risen to 146.7 km/h. Velocity itself hadn't dropped significantly. Nevertheless, batted balls were going up, turning into extra-base hits and home runs.

This is the key point.

Inoue's problem in 2025 wasn't a "lack of power." It was that "batters had learned and established a way to beat Inoue." This is the world of professional sports. If you stay in the same place, you are eliminated. It is a world where only those who ascend are allowed to survive.

The pitch value of the slider was also symbolic. The slider, which was +8.2 in 2024, dropped to -4.9 in 2025. Slider usage fell to 20.7%, but it was still significant as the second pitch. The successful pitch of the previous year became the pitch that dragged him down the next year.

Furthermore, while the forkball remained positive at +1.7, the fastball was almost neutral at -0.2, the two-seamer was -2.5, and the curveball was -3.1. Overall, the clear pitches he could "push with" were thinning out.

Given this flow, we can see what the 2026 Inoue has changed.

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1. In 2026, the first thing that changed was the quality of the fastball

The biggest change for Inoue in 2026 is the fastball.

The average velocity has entered the 148 km/h range. Public data shows an average fastball of 148.1 km/h and a max of 152 km/h. Looking at the average per game over 5 starts, it is quite stable at 148.3, 148.3, 147.9, 148.0, and 148.1 km/h.

He didn't just throw a fast ball once. He maintains around 148 km/h every outing.

Since the average fastball in 2025 was 146.7 km/h, this is an increase of about 1.4 km/h. For a left-handed starter, this gain is significant.

However, if it were just velocity, it would end at "he got faster."

What's truly important is that the results of the fastball have changed.

In the NPB Data Store pitch trends, the 2026 fastball has 232 pitches, a 50.5% usage rate, and an average of 148.11 km/h. Whiff% is 20.56%, CSW% is 36.64%, and the ground ball rate is 57.1%.

In the NPB Scholar classification as well, the four-seamer has 223 pitches, a 48.6% usage rate, and an average of 148.4 km/h. Stuff+ is 105.7, Location+ is 107.7, Zone% is 59.2%, Whiff% is 18.8%, and Called Strike% is 26.0%. Not just velocity, but both pitch quality and location evaluations are above average.

The 2025 fastball had a Whiff% of 14.14%, CSW% of 26.30%, ground ball rate of 42.1%, and fly ball rate of 53.7%.

In other words, the 2026 fastball is getting more whiffs, more called strikes, and yet the batted balls aren't going up as much as the previous year.

This is quite significant.

Usually, when people talk about improving a fastball, they focus on "increased whiffs." Of course, that's correct. But in Inoue's case, the fact that the fastball's ground ball rate rose from 42.1% to 57.1% is more important for his pitching design.

The issue in 2025 was "batted balls going up." In 2026, Inoue is starting to fix that issue with the fastball itself.

It's the same with pitch value.

The 2026 fastball is +6.2, or +2.87 per 100 pitches. Considering 2025 was -0.2, it's almost a different pitch.

Inoue's pitching this year has the fastball back as the main protagonist.

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1. However, it's not just a one-pitch fastball approach. Rather, the "fastball velocity band" has expanded

If you only see the 2026 Inoue as a "pitcher whose fastball got faster," you're looking at it a bit shallowly.

The essence lies in the fact that the types of fast pitches have increased.

The 2025 pitch mix was: Fastball 47.7%, Slider 20.7%, Forkball 14.0%, Two-seamer 6.6%, Cutter 4.7%, Curveball 6.2%.

In 2026, it is: Fastball 50.5%, Forkball 14.2%, Slider 12.2%, Two-seamer 10.5%, Cutter 10.2%, Curveball 2.2%.

NPB Scholar classifies it as: Four-seamer 48.6%, Forkball 14.8%, Sinker 12.4%, Slider 11.8%, Cutter 9.8%, Curveball 2.4%. While the denominators and pitch names fluctuate by site, the structure is the same. Centered on the fastball family, he has lined up the forkball, sinker-types, cutter, and slider all in the 10% range.

Three things have changed significantly:

The slider has decreased.

The curveball has decreased.

The two-seamer and cutter have increased.

In other words, instead of leaning toward slow pitches or big breaking balls, he has shifted toward making fine adjustments within the velocity band close to the fastball.

This is a very natural response to the 2025 issues.

If batters are creating angles, instead of just increasing dropping pitches, you use pitches that look like fastballs to move off the barrel. The moment a batter times the fastball, you jam them with a two-seamer. You miss the barrel with a cutter. You let it escape downward with a forkball.

Inoue didn't go for a change-of-pace style with large velocity gaps.

He is going in the direction of shifting away from the batter's swing path while maintaining high velocity.

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1. The forkball is not just a "dropping pitch," but a very strong finisher

Inoue's 2026 forkball cannot be ignored.

Public data shows the forkball has 65 pitches, a 14.2% usage rate, and an average of 131.4 km/h. Opponent batting average is .100, with 9 strikeouts. Whiff% is 58.0%, and SwStr% is 30.77%.

In NPB Scholar, the forkball has 68 pitches, a 14.8% usage rate, and an average of 132.0 km/h. Stuff+ is 114.0, the highest among Inoue's major pitches. While Zone% is low at 20.6%, Chase% is 53.7% and Whiff% is 48.8%. This is very clearly a pitch to "make them swing and end it," rather than a "pitch to get counts in the zone."

This is clearly a finishing pitch.

The fastball is in the 148 km/h range, the two-seamer in the 147 km/h range, the cutter in the 134 km/h range, and the forkball in the 131 km/h range. Inoue's forkball isn't an extremely slow pitch. It drops about 17 km/h from the fastball, but it's fast enough for a lefty's forkball.

And the whiff rate when this pitch is swung at is extremely high.

However, there is a point of caution.

The forkball's Strike% is low at 21.54%. This means it's a pitch that only gains value when the batter swings, rather than one thrown into the zone to get counts.

In other words, the forkball isn't a pitch that sets the count on its own.

By using the fastball, cutter, and two-seamer to force the batter's eyes and swing timing forward, he finally drops it with the forkball. Because that setup is established, the forkball whiffs are born.

This is the structure of the 2026 Inoue.

He's not suppressing hitters because the forkball is good.

Because the fastball has become stronger and the options in the fastball velocity band have increased, the forkball is functioning better as a finishing pitch.

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1. The cutter is "unfinished, but necessary"

The hardest pitch to evaluate for the 2026 Inoue is the cutter.

Usage increased from 4.7% in 2025 to 10.2% in 2026. Average velocity is 134.3 km/h. Whiff% is 46.88%, SwStr% is 23.40%, and Chase% is 51.72%.

In NPB Scholar, the cutter has a 9.8% usage rate, 135.0 km/h average, and 51.7% Chase%. On the other hand, wOBA is .434 and xwOBA is .416, which are quite heavy. In other words, it has the power to make them swing, but the damage when hit is large.

When he makes them swing, he gets a lot of whiffs.

On the other hand, the batting average against is .294 with 1 home run allowed. Pitch value is also significantly negative at -3.9, or -8.14 per 100 pitches.

So, the cutter is not currently a "pitch producing results."

However, that doesn't mean it's unnecessary.

The role of the cutter is to create a fast horizontal shift just below the fastball. Inoue's fastball is in the 148 km/h range. The forkball is in the 131 km/h range. The slider is in the 126 km/h range. By having a 134 km/h cutter here, the batter must consider the option of a "pitch close to fastball speed, but off the barrel."

In 2025, Inoue's slider and forkball became easy to see as big breaking balls, and when batters timed the fastball, the ball went up.

In 2026, Inoue is placing the cutter in between.

Therefore, the cutter cannot be fully evaluated by pitch value alone. Of course, the current -3.9 needs improvement. The batting average against is high. A mistake will lead to an extra-base hit.

But in terms of pitching design, it is a necessary pitch.

If this pitch can be consistently located on the edges of the zone, Inoue's fastball will live even more.

The current cutter is not a finished product; it is the very growth potential of the 2026 Inoue.

And if I were to suggest a word regarding that pitch design,

I would answer if asked by the man himself, but for now, I will refrain from making it public.

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1. The two-seamer is not a "pitch with bad results," but a "pitch for ground ball design"

It's the same for the two-seamer.

The 2026 two-seamer has 48 pitches, a 10.5% usage rate, and an average of 147.2 km/h. It's in almost the same velocity band as the fastball.

In NPB Scholar, it's labeled as a sinker, with 57 pitches, 12.4% usage, and 147.6 km/h average. Vertical movement is +44.1 cm, and horizontal movement is -30.6 cm. Compared to the four-seamer's vertical movement of +51.4 cm and horizontal movement of -17.3 cm, it's a pitch in the same velocity band that runs more toward the arm side.

Whiff% is 30.43%, and the ground ball rate is 100.0%. Of course, because the number of batted balls is small, we shouldn't treat the 100% figure as a large sample. Still, the intent is clear.

This pitch is less about getting whiffs and more about looking like a fastball to miss the barrel and induce ground balls.

However, the challenges are also clear.

The batting average against is .500 with 4 walks. Pitch value is also -1.7. There is still coarseness in control and usage.

Still, the reason Inoue is increasing this pitch is clear.

In 2025, Inoue had a fly ball rate of 47.2% and allowed 15 home runs. Batted balls going up was the biggest issue. From there, in 2026, the overall ground ball rate has risen significantly. In the NPB Data Store pitch trends, the overall GB% rose from 49.0% in 2025 to 65.4% in 2026. In other tallies, the ground ball rate has risen to about 60%.

This is not a coincidence.

By not only increasing the output of the fastball but also mixing in two-seamers in the same velocity band, he is lowering the batter's launch angle.

So the two-seamer is also an "unfinished but necessary pitch" at this point.

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1. The slider hasn't disappeared; its role has changed

The slider that supported the 2024 Inoue has seen its usage drop in 2026.

In 2024, it was 26.9%.

2025 was 20.7%.

2026 is around 12%.

Looking at these numbers alone, it might look like he abandoned the slider.

But that's not the case.

The 2026 slider has 56 pitches, averaging 126.2 km/h. Whiff% is 29.17% and CSW% is 50.0%. In the pitch-by-pitch table of "Enjoying Pro Baseball with Data," the slider's called strike rate is high in the 39% range.

In NPB Scholar as well, the slider has a Location+ of 111.2, Called Strike% of 40.7, and CSW% of 50.0. Stuff+ is 94.8, which isn't outstanding, but it's a pitch that creates value through location and usage.

In other words, it's functioning as a pitch to get called strikes, not just whiffs.

The 2024 slider was a lead actor. The 2026 slider is closer to a supporting line that bolsters the fastball, forkball, and the horizontal shifts in the fastball band.

This change is not a bad thing.

In fact, considering the slider's pitch value dropped significantly in 2025, it's natural for Inoue to try to break away from slider dependency.

What the current Inoue needs is not to return the slider to its 2024 state.

It's to use the fastball and forkball as the axis, practicalize the cutter and two-seamer, and then use the slider as a "fourth pitch that can also get called strikes."

The slider went from a lead role to a supporting role.

However, that supporting role is quite important.

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1. Zone Design—Reducing the Heart, Winning in the Shadow

To understand Inoue's 2026, the area around the zone is also important.

Looking at the pitch percentage in the attack zones, in 2026, Heart is 21.8%, Shadow is 47.6%, Chase is 25.8%, and Waste is 4.8%.

NPB Scholar's Location+ is 106.6, which puts him in the upper percentiles. This is the core of the 2026 Inoue. If it were just that the pitches got stronger, it would be a story about Stuff+, but in Inoue's case, Location+ shows up even more strongly.

The ratio of pitches to the Heart, or near the middle, is low, and pitches to the Shadow, or the boundaries of the zone, are very frequent.

In 2025, Heart was 24.2%, Shadow 42.9%, Chase 28.3%, and Waste 4.7%. In 2026, he has further reduced the Heart and shifted toward the Shadow.

This is consistent with his current pitch mix.

Push with the fastball.

Move to the arm side with the two-seamer.

Shift in the opposite direction with the cutter.

Drop it down with the forkball.

Create called strikes and horizontal width with the slider.

This configuration is better suited for forcing the batter to make a decision at the boundary rather than throwing into the middle to overpower them with force.

In fact, in terms of run value by zone, the 2026 Inoue is creating plus value in the Shadow. While the value when swung at in the Heart is negative, in the Shadow, the total of swings, called strikes, and all pitches is positive. In other words, he has become a pitcher who creates value at the boundaries rather than winning in the sweet spots.

In the NPB Scholar metric explanation, Location+ is explained as not just the strike zone rate, but looking at which courses were thrown, whether he can miss after getting ahead, and whether he can use balls in situations where they should be used.

From this perspective, Inoue's 2026 is closer to being read as "he changed to a pitch mix that can compete at the boundaries" rather than "he's throwing more strikes."

This is also a point I want to emphasize more than the previous article.

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1. The biggest change for the 2026 Inoue is "Contact Quality" rather than whiffs

In 2026, Inoue's strikeouts are increasing.

A K% of 28.0% is quite high. In the NPB Data Store percentiles, K% is toward the top. A K-BB% of 22.0% is also excellent.

However, if you talk about Inoue's change only in terms of strikeouts, you'll miss the point.

The essence is that the way he is being contacted has changed.

In the NPB Data Store pitch trends, the overall Contact% has dropped from 71.60% in 2025 to 66.24% in 2026. Whiff% has risen from 28.40% to 33.76%. CSW% has risen from 29.56% to 36.38%.

In other words, it's easier to get a whiff when swung at, called strikes have increased, and the batter's contact itself has become more difficult.

Furthermore, the overall GB% has risen from 49.0% to 65.4%. The fly ball rate has dropped from 46.5% to 32.7%.

This is almost a direct answer to the 2025 weakness.

In 2025, batters were creating angles against Inoue.

In 2026, while increasing whiffs, Inoue is simultaneously lowering the launch angle.

This duality is huge.

Whiff-type pitchers can sometimes have balls in the zone hit hard. Ground ball-type pitchers can have fewer strikeouts and be easily influenced by defense or BABIP.

But the 2026 Inoue has a 28.0% strikeout rate and a high ground ball rate.

This combination is extremely valuable for a starting pitcher.

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1. So, what is still missing?

Looking this far, the 2026 Inoue looks quite good.

In fact, the performance is good.

However, it's too early to call it a finished form.

The reason is that the individual value of the pitches he increased is not yet stable.

The two-seamer has a pitch value of -1.7.

The cutter is -3.9.

The forkball is also excellent in batting average and whiffs on public sites, but in other tallies, the pitch value is slightly negative.

In other words, the 2026 Inoue hasn't "completed a new pitch design."

Because the fastball output rose and he placed new pitches around it, the overall shape of his pitching has improved. However, he hasn't yet reached the stage where the two-seamer and cutter create plus value on their own.

This is the future fork in the road.

If the two-seamer stabilizes on the edges of the strike zone, the cutter doesn't catch too much of the plate, and the forkball continues to function as the follow-up to making them swing, Inoue will be quite strong.

Conversely, if opposing lineups start to lay off the two-seamer and cutter and force him back to a two-choice game of fastball and forkball, the risk of batted balls going up like in 2025 will emerge again.

The current Inoue is not a completed ace, but rather in a stage where he is progressing through a design change to become an ace-level pitcher in a very good way.

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1. Haruto Inoue's Pitching Philosophy

Let's organize.

In 2024, Inoue found an answer as a first-team starter with the fastball and slider.

In 2025, Inoue struggled with batted balls going up and home runs. It wasn't that the strikeout-to-walk balance was extremely bad. The problem was that batters were creating strong angles.

In 2026, Inoue is providing a very clear answer to that challenge.

Raise the average fastball velocity to the 148 km/h range.

Increase whiffs and called strikes with that fastball.

Increase two-seamers and cutters to miss the barrel while staying in the fastball velocity band.

Use the forkball as a finishing pitch.

Move the slider from a lead role to a supporting line that creates called strikes and horizontal width.

Reduce the Heart and compete in the Shadow.

This isn't "increasing pitch types."

The expression "reinstalling the pitching OS" is closer.

The current Haruto Inoue is not just a hard-throwing lefty. While he looks like a power lefty, he also possesses the elements and potential of a finesse lefty—he is a presence that can become a super pitcher.

Therefore, what's important when looking at the 2026 Inoue isn't the surface ERA of 2.12.

That the fastball's Whiff% and CSW% rose.

That the fastball's ground ball rate rose.

That the overall fly ball rate dropped.

That the two-seamer and cutter increased.

That he started creating value in the Shadow.

When you line up these five, Inoue's current position becomes quite clear.

He hasn't recovered.

He is trying to become a different pitcher.

And that direction is quite modern.

Instead of dodging with slow breaking balls, you shift within the fastball band.

Instead of only chasing whiffs, you also destroy the launch angle.

Instead of a power struggle in the middle, you force a decision at the boundary.

This is the pitching philosophy of the 2026 Haruto Inoue.

It's not finished yet.

That's why it's interesting from here on.

When the two-seamer and cutter truly become weapons, Haruto Inoue will exceed his 2024 breakout.

At that time, he will be a pitcher talked about not just as a "young Giants lefty," but as one of the top starting lefties in the league.

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Reference Notes

References centered on tallies as of May 13, 2026. Since pitch classification and FIP have definition differences depending on the site, changes where the direction matches across multiple sources were prioritized in the text. For NPB Scholar individual data, the 2026 season tally for Haruto Inoue was referenced.

Main sources:

• NPB data-related public pages
• NPB Data Store pitch trends, velocity trends, sabermetrics pages
• "Enjoying Pro Baseball with Data" pitch-by-pitch whiff rate and called strike rate pages
• NPB Scholar Haruto Inoue dashboard, Stuff+ / Location+ metric explanations