Japanese Rookie Roki Sasaki Becomes Dodgers’ Bullpen Edge Ahead of 2025 World Series

The bullpen of the Los Angeles Dodgers could be the equalizer in their quest to become the first National League team to win back-to-back World Series titles since the Cincinnati Reds did so in 1975 and 1976. With another championship, the Dodgers would claim their ninth in franchise history when they begin their matchup in Game One on Friday, October 24, against the Toronto Blue Jays at 8 p.m. EDT on FOX.

This is the real World Series — after all, it’s the United States vs. Canada’s lone Major League Baseball franchise.

Dodgers Dominant Through the 2025 Postseason

The Dodgers’ pitching staff has been nearly unstoppable during the 2025 postseason. Through 10 games, Los Angeles is 9-1, with four saves and eight holds, logging 92 innings while allowing 56 hits, 25 earned runs, and just four home runs. The staff has walked 38, struck out 104, and posted a collective 2.45 ERA.

Roki Sasaki’s Breakout in the Bullpen

Japanese rookie right-hander Roki Sasaki has been the centerpiece of the Dodgers’ pitching staff during this magical postseason run.

Sasaki has made seven appearances in relief, recording three saves and one hold while firing eight innings with just three hits allowed, one earned run, two walks, and six strikeouts. He enters the World Series with a 6.8 K/9, a 0.63 WHIP, and a 1.13 ERA in his first Major League season after coming over from Japan, where he spent four years with the Chiba Lotte Marines from 2021 through 2024.

Roki Sasaki has been dominant out of the bullpen this #Postseason ???? pic.twitter.com/TYJg2KyQDJ

— MLB (@MLB) October 23, 2025

Dodgers relievers Alex Vesia, Blake Treinen, Emmet Sheehan, Anthony Banda, Clayton Kershaw, Jack Dreyer, and Edgardo Henriquez have also filled key roles throughout the 2025 postseason.

From Japan to Chavez Ravine

Sasaki signed with the Dodgers on January 22, 2025, receiving a $6.5 million signing bonus. Because he was under the age of 25 at the time, international signing regulations required him to sign a minor league contract. Both Baseball America and MLB.com ranked Sasaki as the No. 1 overall prospect entering the 2025 season.

The 23-year-old from Rikuzentakata, Iwate, Japan was transferred from the 15-day to the 60-day injured list on June 20 with a right shoulder impingement before being activated on September 24.

Sasaki made two late-season bullpen appearances — on the road against the Arizona Diamondbacks (Sept. 24) and Seattle Mariners (Sept. 26) — without allowing an earned run. He threw two innings, gave up one hit, and struck out four to close out the regular season.

2025 Regular Season Recap

In his rookie year at Chavez Ravine, Sasaki appeared in 10 games and made eight starts, going 1-1 with a 4.46 ERA across 36.1 innings. He allowed 30 hits, 18 earned runs, six home runs, 22 walks, and struck out 28 batters, finishing with a 1.431 WHIP.

According to his Baseball Savant profile, Sasaki allowed only six home runs off his four-seam fastball in 2025.

His four-seam fastball averages 96.1 mph, with opposing hitters batting .256 against it, producing an 11.1% whiff rate and a 17.5% putaway rate.

Sasaki’s split-finger fastball averages 84.9 mph, holding opponents to a .146 average with a 37.2% whiff rate and a 16.9% putaway rate.

His slider, another effective weapon, sits at 82 mph and generates a 33.3% whiff rate and a 12.5% putaway rate.

Historic Achievements in Japan

During his four seasons with Chiba Lotte, Sasaki threw a perfect game on April 10, 2022, became a two-time NPB All-Star (2022 and 2023), and received the Chiba City Special Award “New Era Hometown Impressive Award” in 2022. That same year, he struck out 19 batters in a single game, setting an NPB record, and recorded 13 consecutive strikeouts, a world record.

WBC Legacy and 2026 Outlook

Sasaki played a key role in Japan’s 2023 World Baseball Classic championship, helping lead the team managed by Hideki Kuriyama to a 3–2 win over the United States in the final at loanDepot Park in Miami.

He went 1-0 in two starts, throwing 7.2 innings with a 3.52 ERA, allowing seven hits, three earned runs, one home run, and two walks, while striking out 11. Opponents hit just .233 against him.

With Hirokazu Ibata set to manage Japan in the 2026 World Baseball Classic, the national team will be watching closely to determine Sasaki’s role — whether as a starter or closer — for Pool B at the Tokyo Dome, where Japan will face South Korea, Chinese Taipei, Australia, and the Czech Republic from March 5–10.