Yoshinobu Yamamoto Has Stepped Into Ace Role In 2nd Year With Dodgers

The Dodgers have been the talk of baseball for the past couple of years, creating one of the greatest assemblages of talent in the history of the game. Obviously, the crown jewel of this wave of talent acquisition was dual-threat Shohei Ohtani, slated to make his Dodger pitching debut later this season while reigning as one of the game’s greatest hitters.

Ohtani’s move across town from the Angels has made Chavez Ravine a destination for high-end Japanese player talent. The last two offseasons have seen the Dodgers land the premier NPB pitching free agent – first Yoshinobu Yamamoto and then Roki Sasaki.

Yamamoto inked a 12-year, $325 million deal entering 2024, his age 25 season. His first full season, on balance, was somewhat of a disappointment. Qualitatively, he was fine, with a 28.5% K rate and 6.0% BB rate, an average contact management performance (101 Adjusted Contact Score) , and a 79 “Tru” ERA- (my batted ball-based proxy for ERA- and FIP-). That mark didn’t quite measure up to his 74 and 64 marks in those more mainstream categories.

The problem was bulk. Yamamoto tossed only 90 innings last season, missing time due to triceps tightness. That actually placed him third in that department on the World Champions’ staff, behind Gavin Stone (140 1/3) and Tyler Glasnow (134). Yamamoto actually only nosed out James Paxton by 2/3 of an inning for that third spot. To his credit, Yamamoto was instrumental in the Dodger postseason drive, making a start in each series, and having his best outing in the World Series against the Yankees.

Each season, I issue pitch grades for all of the qualifying pitches for starters with 135 or more innings pitched, based on their bat-missing and contact management performances relative to the league. While Yamamoto didn’t meet that innings standard, I have gone back and calculated grades for his pitches anyway. His arsenal graded out right around league average – his splitter a little above with a “B+”, his four-seamer a little below at “C+”. All three offerings were in the average range with regard to both bat-missing and contact management, with the exception of the splitter’s above average (19.4% pitch-specific whiff rate) and the four-seamer’s below average bat-missing (6.9%).

Now it must be emphasized that a somewhat above average splitter is one hell of a pitch – the splitter was neck-and-neck with the changeup for the title of the most effective offering in the game last season, with an 88.9 Adjusted Contact Score and 16.2% whiff rate. Yamamoto’s checked in at 91 and 19.4%. He threw the pitch 24.2% of the time in 2024.

Now here we are in 2025, and Yamamoto has been even better qualitatively in the early going. He stands at 4-2, 0.90, with a 49/13 K/BB ratio in 40 innings, allowing just 24 hits. His K rate has ballooned to 32.0% (though his BB rate has also increased to 8.5%).

Now it’s way too early to be issuing any pitch grades, but we can peel back a layer or two to identify some of the reasons for his improvement. We can then also make some educated guesses as to whether it is sustainable.

First of all, Yamamoto’s swing-and-miss rate has shot up from 12.0% to 13.8%, explaining the increase in his K rate. Breaking that down on a pitch-by-pitch basis, the reasons for this are clear – he’s throwing his splitter more, and the pitch’s quality has dramatically improved.

Its average velocity is up from 90.2 mph in 2024 to 91.0 mph in 2025. He is now throwing the splitter 29.5% of the time – among 2024 pitch grade qualifiers, only Alex Cobb, Kevin Gausman and Taijuan Walker threw theirs more often. Even more importantly, his pitch-specific whiff rate has shot up to 24.0% – only countryman Shota Imanaga’s “A+” splitter (26.0%) tops Yamamoto’s 2025-to-date whiff rate.

His splitter has also been an exceptional contact management pitch in the early going. In 2024, Yamamoto yielded 80 ground balls, 27 of them on the splitter. Thus far in 2025, he’s yielded 48 grounders, 22 of them on the splitter. His overall average launch angle allowed is down from 7.8 degrees in 2024 to 2.7 in 2025. His grounder rate has rocketed from 47.9% to 61.5%. This has greatly improved his overall contact management performance – he has posted an 82 Adjusted Contact Score to date, despite allowing even harder average exit speeds across all batted balls types than in 2024. Currently, his 64 “Tru”- is right in range of his 57 FIP- though far above his 22 ERA-.

There are some red – or at least orange – flags in place here that should temper enthusiasm for his performance moving forward, however. His 16.5% liner rate allowed is going to regress upward, there’s no getting around that. He’s also been very lucky on grounders, with a 39 Unadjusted but a 92 Adjusted Grounder Contact Score. But neither of those is a huge deal – even with an average contact management performance, Yamamoto could be a Cy Young contender.

The big issue for me is over-reliance on the splitter. His four-seamer whiff rate has dropped even further to 5.6%, so in the early going this most important of offerings is certainly no better than the “C+” pitch was in 2024. The four-seamer might be decreasing in usage, and the worst single pitch in the game – but the great ones have great ones. Pitchers who rely too much on splitters or splitter-equivalents, like Kodai Senga’s forkball, often get hurt. Or like Kevin Gausman, a decline in the effectiveness of their out pitch can collapse their entire repertoire.

So let’s enjoy what we’re currently seeing from Yoshinobu Yamamoto. He’s riding a lethal out pitch as hard as he can. He’s going to need improvement from his other offerings to improve his overall risk/reward profile, however. Splitter-first to splitter-only starters have a limited shelf life, at least with regard to excellence.