Roki Sasaki Pitch Data: How Will His Arsenal Translate To MLB?

Roki Sasaki’s Pitch Mix

In many ways, Sasaki has a traditional Japanese mix with a four-seam fastball, splitter and slider. Sasaki’s outstanding power across his arsenal is truly an outlier trait. His fastball ranged from 97-99 mph and touched 102.5 mph at peak over the last two seasons. 

Sasaki most frequently throws his splitter among his secondaries and regularly uses it against both lefthanded and righthanded batters. He also throws his slider against righthanders as frequently as his fastball. 

Pitch Type	Average Usage	Year
Fastball	49%	2024
Splitter	31%	2024
Slider	18%	2024

Pitch Type	Average Usage	Year
Fastball	49%	2023
Splitter	35%	2023
Slider	14%	2023

As you can see, Sasaki’s fastball usage over the last two seasons (49%) remained incredibly consistent. He threw the splitter slightly less in 2024 in favor of greater slider usage. He clearly has a defined arsenal and consistent usage patterns over multiple seasons. Let’s dive a little deeper into each pitch. 

Fastball 

Sasaki’s prolific fastball has been a selling point dating back to when he surpassed Shohei Ohtani as Japan’s hardest-throwing high schooler by touching 101 mph. But Sasaki saw a drop in his average velocity, induced vertical break and, subsequently, his swinging strike rate. There’s a marked difference evaluating Sasaki’s fastball between the two seasons. 

Year	Pitch Type	Velocity	Max Velocity	IVB	HB	VAA	EXT	RH
2023	Fastball	99 mph	103 mph	18.1	-16.7	-4.7	6.3	6
2024	Fastball	97.1 mph	101 mph	16.1	-14.2	-5	7	6

Clearly, something changed. Sasaki lost nearly two mph in average velocity, two inches of induced vertical break and his approach angle got steeper. None of these are good developments for a pitch rated as double-plus offering. 

Sasaki’s unchanged released height despite adding nearly a foot of extension is truly unusual. This can likely be explained by a change in tooling as Hawkeye became more prevalent in many NPB parks. Hawkeye measures extension and movement more accurately and can account for deltas in certain metrics compared to Trackman devices. Typically, such a significant change in extension would yield even better results. It’s hard to draw any significant conclusions on his extension because the calibration of devices from park to park can vary greatly. 

Taking his 2024 numbers at face value, Sasaki lost ride and had a steeper, less horizontal approach to the plate. Perhaps this is also a product of the tooling change in parks and not an actual change in movement. It’s unusual for a pitcher to add that much extension and not see a drop in his release height. There are also potential explanations beyond just different measuring devices. Sasaki’s arm slot does look slightly higher than in 2023, and would likely offset some of the expected drop in release height that comes with any added extension. 

Still, that doesn’t give us a perfect explanation for changes in shape. Was there a grip change on his fastball that led to him losing efficiency that would impact both induced vertical break and fastball plane? I’d need higher speed video in order to determine that, but there was likely some change. 

The velocity drop is certainly concerning and likely can’t be explained by just the arrival of Hawkeye, especially considering Sasaki was not particularly durable over the early part of his NPB career. Regardless of whether there are differences in fastball shape, it’s hard to argue against the significant jump in hitter’s production against the pitch. 

Year	Pitch Type	Whiff%	Strike%	Chase%	GB%	OPS
2023	Fastball	24%	73%	29%	53%	.572
2024	Fastball	13%	71%	26%	50%	.743

Sasaki’s whiff rate dropped by 45% compared to a 171-point OPS increase. These poor results are certainly the product of diminished fastball quality in 2024. These are likely all fixable issues that a major league player development team would likely have a plan to triage. 

Despite the concerns, Sasaki’s fastball still has plus fastball velocity, good traits and consistently drives groundballs at a high rate. The differences between the NPB and MLB ball will likely lead to a drop in carry and horizontal break. So while the tooling change may explain some of the added extension, it doesn’t explain the drop in results or velocity. The fastball is still a plus pitch but it’s hard to know what Sasaki’s exact shape will look like in MLB. 

Splitter

Sasaki’s 88-89 mph splitter is easily his best pitch with virtually unchanged movement compared to 2023. It moves similarly to a gyro slider but with a preference for armside and not gloveside movement. This uncertainty and heavy reliance on gyro make the pitch unpredictable with an average spin rate of 642 rpm in 2024. It’s a unique pitch that puts pressure on batters to lay off of it. 

Year	Pitch Type	Velocity	Spin	IVB	HB	VAA	EXT
2023	Splitter	89.7	1441	-0.8	-3.7	-8.5	6
2024	Splitter	88.3	642	-0.5	-0.7	-8.1	7.1

There were some changes in the data year-over-year, but once again it might be a matter of the tooling change. The drop in spin is a positive for a splitter and the pitch would have one of the lowest spin rates in MLB. Video shows a splitter with nasty movement that is hard to pick up out of the hand. It leaves the hand with similar plane to the fastball with late dynamic drop and tail. The pitch continually elicited ugly swings and misses. 

Year	Pitch Type	Whiff%	Strike%	Chase%	Swing%	SwStr%	GB%	OPS
2023	Splitter	53%	65%	48%	56%	30%	73%	.236
2024	Splitter	56%	55%	34%	43%	24%	60%	.340

While Sasaki’s splitter remained elite in 2024, there are signs it backed up compared to 2023. His whiff rate remained the same but overall swings against the pitch dropped by 30%. That isn’t reflected in the whiff rate, which simply looks at the number of whiffs per swing. Instead, this development shows in his swinging strike rate drop and overall strike rate drop. 

The drop in fastball quality may explain why hitters laid off the splitter more consistently. The pitch was still highly effective but is another wrinkle in a downturn in Sasaki’s results in 2024. Make no mistake, the splitter is still a double-plus pitch that generates swings and misses plus a high rate of groundballs. This is likely another blip that a MLB team would address upon signing. 

Slider

Sasaki’s above-average slider receives the least amount of fanfare among his three pitches. His velocity dropped by four mph in 2024. We saw Sasaki’s slider si in the upper 80s during the World Baseball Classic at a park that utilizes Hawkeye, so the change in ball-tracking systems doesn’t explain the drop in velocity. 

Year	Pitch Type	Velocity	Spin	IVB	HB	VAA	HAA
2023	Slider	87.7	2102	-0.7	9.2	-7.8	-3.6
2024	Slider	83.7	1912	-0.2	9.9	-8.2	-4

The year-over-year power clearly disappeared, yet the performance actually improved. Sasaki threw his slider more frequently and shaved off around 90 points in OPS. He did get less chases on the pitch in 2024 and saw a slight drop in swing rate and swinging strike rate, but saw a four percent rise in called strikes (20% vs. 24%). He also commanded his slider better in 2024. 

Year	Pitch Type	Whiff%	Strike%	Chase%	Swing%	SwStr%	GB%	OPS
2023	Slider	45%	60%	33%	40%	18%	46%	.421
2024	Slider	40%	62%	26%	38%	15%	54%	.309

Obviously, there are some things to like. The slider is a swing-and-miss offering, and his ability to drive more groundball contact against it is a positive. He threw the pitch in-zone more often and it led to better results. The velocity dip was unusual, especially considering the movement profile of the pitch didn’t change. 

Sasaki is an elite pitching talent who combines velocity, movement and consistent strike-throwing. There are still durability concerns, particularly in light of his velocity drop across his fastball and slider in 2024. That said, Sasaki could make potential mechanical improvements, like many young pitchers. A better version of Sasaki may arrive in the not-so-distant future.