What to Expect From Japanese Pitcher Roki Sasaki in MLB

The 23-year-old will become one of baseball's top free agents once he's posted by the Chiba Lotte Marines. But what will he bring to the table as a big leaguer?

Sasaki is expected to be one of the biggest draws in free agency this winter. / Sam Navarro-Imagn Images

The MLB offseason changed dramatically Saturday with the announcement by the Chiba Lotte Marines of Nippon Pro Baseball that they will post star pitcher Roki Sasaki. The righthander is as attractive a free agent to all 30 teams as it gets: young (23 years old), dominant (2.02 career ERA and 11.5 strikeouts per nine innings) and cheap (a signing bonus of $2 million or so and a minimum rookie salary).

Once the Marines officially post Sasaki, he has 45 days to come to agreement with an MLB team. If he is posted this month, he will likely sign before Dec. 15, when a 30-day dead period begins, after which clubs’ international signing pools are reset. If he is posted next month, he likely signs after Jan. 15, when pool money is higher (and thus, his bonus).

Because the cost of acquisition is so cheap—like getting a major league ready 1–1 draft pick on a discount—his free agency is not likely to hold up the market. The Dodgers, for instance, are still in the marker for an elite starting pitcher in addition to Sasaki, according to a source familiar with their plans.

Who is Sasaki? What does his stuff look like? Who are his comps? Why is he giving up hundreds of millions of dollars to join MLB now? You’ve got questions. We’ve got answers.

How good is Sasaki?

“His ceiling is he’s the best pitcher in the world,” said one MLB talent evaluator who has watched him in person several times. “[But] he’s definitely not a finished product. Most people in Japan would agree with that.”

What does he throw?

1. Four-seam fastball with elite velocity and movement

Sasaki’s heater this year averaged 96.9 mph, down from 98.9 mph in 2023. It has 17 inches of induced vertical break, a measurement of “ride.” Only six MLB starters last season averaged at least 96 mph with that much vert: Taj Bradley, Dylan Cease, MacKenzie Gore, Hunter Brown, Luis Gil and Jared Jones.

That’s not all. Sasaki’s four-seamer also has ridiculous arm-side run: 12 inches. Only one MLB pitcher this year had that combination of so much velocity, ride and run on a four-seamer: Philadelphia Phillies reliever Jeff Hoffman.

“The movement profile on his fastball is elite,” the evaluator said. 

2. Elite split-finger fastball

The low-90s divebomber, thrown with a wide, four-seam grip, is a swing-and-miss pitch. “His command of the split is phenomenal,” said one scout.

3. Average slider

The 84-mph breaking pitch with gyro spin is not a great pitch yet. The scout said Sasaki threw it more often this year as if to demonstrate more “pitchability” to MLB teams rather than being labeled as a two-pitch pitcher. The scout said the slider is “too slow” with a poor movement profile and will be tightened up by the team that acquires him.

What about his mechanics?

At 6' 4" and 203 pounds, Sasaki has grown since the Marines signed him (6' 2", 187). He is a hyper-flexible, fast-moving athlete with a high leg kick, long stride, high three-quarters delivery and excellent arm deceleration. His athleticism allows him to repeat his delivery, making him a premier strike thrower.

On the quirky side, he is a wrist-wrapper (as he takes the ball behind him, the wrist flips, with the palm side of the hand up) in the manner of David Cone or a young Zack Wheeler. He has a somewhat weak front side in which he allows the glove hand to drop slightly rather than pulling it in.

Best comp in terms of how his body and arm work: Wheeler, another hyper-fast mover who is about the same size (6' 4", 195), but Sasaki has a higher arm slot. (Wheeler quieted his wrist wrap after his Tommy John surgery.)

What are the concerns about Sasaki?

1. Decreased velocity over the last two years.

2. No established durability.

3. Fastball movement profile may adjust downward with the difference between NPB and MLB baseballs. 

As a comparison, Yoshinobu Yamamoto gave up just two home runs in 164 innings for Orix in 2023. He gave up seven homers in 90 innings with the Dodgers this year, including three on his 95.5-mph four-seamer, which had below average results in movement and batting average against (.262).

Is he a workhorse front-of-the-rotation ace?

Not yet. Sasaki’s career high innings is 129 1/3 in 2022. He should throw no more than about 150 innings this year.

Sasaki was an instrumental part of Japan's 2023 World Baseball Classic title. / Sam Navarro-Imagn Images

What was his development like in Japan?

Sasaki is the product of a new global generation of pitchers being developed more conservatively. Pitchers in Japan once were famed for their “konjo,” or “guts,” in which they pushed themselves beyond their limits. For instance, Daisuke Matsuzaka was celebrated for throwing 250 pitches in a 17-inning complete game in the national high school tournament, known as the Koshien.

That mentality is waning. As a high schooler in 2019, Sasaki was clocked as fast as 101 mph (163 kph) with his fastball, breaking the national record of Shohei Ohtani (160 kph). In the national tournament for Ofunato High School, Sasaki did throw 194 pitches in a 12-inning victory and 129 pitches in a semifinal win three days later, but did not pitch the next day in a loss in the championship game, prompting a flood of calls to the school asking why he didn’t pitch again. Ofunato's manager explained he was protecting Sasaki’s health.

Sasaki was drafted out of high school by the Marines. They brought him along slowly. Former Mets pitcher Masato Yoshii, the team’s pitching coordinator who studied baseball coaching theory at Tsukuba University graduate school, designed his development plan. The Marines permitted Sasaki in his rookie season, 2020, to train and travel with the team but did not allow him to pitch in a game.

In 2021 he threw only 83 1/3 innings while working on his mechanics and physical strength. The team preferred to give him 10 days of rest between starts.

The next season, 2022, was his breakout season. He posted a 2.02 ERA over 129 1/3 innings while coming within three outs of back-to-back perfect games. His manager, Tadahito Iguchi, had decided before the second of those games to pull him at around 100 pitches.

Sasaki’s innings fell to 91 in 2023 and 111 this year, in part due to arm soreness and an oblique issue.

How will an MLB team handle Sasaki?

He is going to pitch every sixth or seventh day. The Dodgers already have Ohtani, Yoshinobu Yamamoto and Tyler Glasnow on that schedule. More and more teams are using six-man rotations or keeping a five-man rotation through off days.

So-called “extra rest” has been the industry standard for more than a decade, with a spike since the pandemic. Four days of rest is a thing of the past. You must go all the way back to 2013 to find the last time the majority of MLB starts were made on less than five days rest.

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If he is one of the best pitchers on the planet, shouldn’t he throw 200 innings?

No. The baseball industry does not ask pitchers to throw 200 innings anymore. Why? Because of the (1) increased velocity, which is a risk factor for injury; (2) increased supply of power relievers, thanks to advances in training and technology; and (3) diminished importance of the regular season, which has prompted clubs to put starting pitchers on six-month workloads to prioritize the expanded postseason.

You don’t need regular season workhorses to win. The Dodgers did not have a qualified pitcher (162 innings in a full season) in 2023 or 2024—after only one such season in their first 135 years (2018).

Until 2017, every one of the 110 full season World Series winners had at least two starters throw 162 innings. Three of the past seven full-season champions have had just one (2023 Rangers) or none (2017 Astros and 2024 Dodgers, does not include combined innings with multiple teams).

From 2011 to 2023, starters who threw 162 innings dropped by more than half, from 93 to 44. We did see an uptick this season to 58, a post-pandemic high. But the trendline remains in a downward shift as far as what MLB teams ask of their starting pitchers:

Sports Illustrated

Why is Sasaki coming to MLB now?

He wants the challenge more than the money. He has been asking the Marines for years to post him, even though if he waited until he's 25, he could secure a contract worth more than $300 million, the way Yamamoto did. Last year Sasaki held out as long as possible before reaching a contract agreement with the Marines, leading to speculation that agreement included an understanding that they would abide by his wish to pursue a career in MLB.

“Last year, sitting there and watching him,” said the scout, “it was like it was too easy for him. It was like watching [Hyun Jin] Ryu in Korea: great pitchers who you thought were not challenged enough. That was especially true in 2022, when he really dominated, maybe not as much this year when his stuff was down a tick.”

Yoshii told reporters: “Of course it's a big blow to the team. However, I played in America, so I understand the feeling. I also understand the feeling of wanting to challenge while still young.

“To be honest, there are some areas where he is incomplete, but I think he can improve himself in America and raise his level.”

In a statement, Sasaki said, “I will do my best to climb up from the minor league contract and become the best player in the world in order to live up to the expectations of everyone and to not have any regrets in my one baseball life.”

What does Sasaki want in his next team?

Nobody knows the answer to this.

Common speculation has the Dodgers as the favorites. He could join Team Japan teammates Ohtani and Yamamoto (whose agent, Joel Wolfe, also is Sasaki’s agent), the defending world champions, a team that has made the playoffs 12 straight years and a team on the West Coast. 

But there is also the Padres, where his good friend and fellow Wolfe client Yu Darvish pitches. And the Cubs, where Wolfe client Seiya Suzuki plays, or the Mets, where Wolfe client Kodai Senga pitches … and well, you get it. We just don’t know his preferences.

Remember what happened when Ohtani was posted. Speculation centered on the Yankees, who squirreled away as much international signing money as they could. Two days after he was posted, Ohtani ruled out the major market teams on the East Coast.

We do know that late this season, executives Andrew Friedman of the Dodgers, David Stearns of the Mets, Mike Hazen of the Diamondbacks and Craig Breslow of the Red Sox were among the many teams to send their top baseball officer to Japan to personally scout Sasaki.

“This is not a one-off where you just sit down with him now,” one evaluator said. “It’s about establishing a relationship.”

It is similar to big-time college recruiting. Next come the face-to-face meetings and the sales jobs. The Yankees had a video from Hideki Matsui lined up to recruit Ohtani before he ruled them out. Last year one team presented Yamamoto, known for throwing a javelin as part of his training regimen, with a javelin decorated with its team logo.

After landing Yamamoto last winter, the Dodgers are one of the favorites to sign Sasaki. / Jayne Kamin-Oncea-Imagn Images

What is Sasaki’s family background?

Sasaki grew up in Rikuzentakata, Iwate Prefecture. He was nine years old and attending elementary school in 2011 when the area was hit hard by the Tohoku earthquake and tsunami. His father and a set of grandparents were killed in the disaster. His home was lost.

He lived temporarily as an evacuee at a nursing home before his mother in 2012 moved him and his two brothers 10 miles away to Ofunato. To remain with friends and teammates, he attended the small high school there rather than ones with more prestigious baseball programs that recruited him.

On the 12th anniversary of the disaster, Sasaki led Japan to a 10–2 victory over the Czech Republic in the World Baseball Classic. He struck out eight and was clocked at 100 mph or more 21 times in less than four innings, including a 101-mph fastball that hit Willie Escala just below the left knee. The next morning Sasaki visited the Czech team’s hotel and presented Escala with two huge bags of candy.

Does Sasaki have a nickname?

“The Monster of the Reiwa Era.” The Reiwa Era is the current and 232nd era of the official calendar of Japan. It began May 1, 2019, the day Naruhito ascended to the throne as the 126th emperor of Japan. The nickname essentially anoints Sasaki as a once-in-a-generation pitcher.