Masataka Yoshida Lost Himself

When Adam Jones compared his former Orix Buffaloes teammate Masataka Yoshida to Juan Soto, he quickly established the lofty expectations that Yoshida would face as he made the transition to the major leagues. The comparison painted a clear picture of the type of batter Yoshida was in Japan. For all of Soto’s success on contact, his truly elite skill is his plate discipline, and the same was true for Yoshida. In five of his seven seasons in Japan, he ran a walk rate higher than his strikeout rate while posting a 176 wRC+ during his career in his home country. In his final year in NPB, he had the second-lowest strikeout rate and second-highest walk rate among qualified batters.

The transition from Asian leagues to the majors has usually been more difficult for batters than for pitchers. High velocity is the greatest concern, but the quality of breaking and offspeed offerings is much higher as well. For Yoshida, his pitch recognition skills seemed like they’d help him overcome these common problems, even if his overall plate discipline suffered a bit. While he wasn’t able to reach the heights of his career in Japan, he did manage to record a 109 wRC+ in his first big league season, though his 0.6 WAR was certainly lower than the Red Sox were expecting when they signed him to a huge five-year deal. His overall value was hurt by some ugly defense in left field; then again, his glove was never his strength. More concerning was that his approach at the plate worsened as the season went on, leading to a dreadful final two months that greatly diminished what otherwise would have been a successful rookie year.

Through the first three months of the season, everything looked like it was working out; he was posting a 129 wRC+ with 8.7% walk rate and an 11.3% strikeout rate. The plate discipline looked like it had made the transition without any fuss, and he was hitting for some power to top it all off. Unfortunately, over the next three months, things took a turn for the worse, dragging his overall line down to where it ended the season. It’s pretty easy to see what the issue was when you look at his rolling strikeout and walk rates during the season.

From July 1 through the end of the season, he took just seven walks total and his strikeout rate jumped to 17.0%. He continued to produce in July, even as he began to lose his plate discipline, but everything crumbled over the final two months, when he slashed .257/.276/.371 and had a 68 wRC+ across 181 plate appearances.

So what happened to his legendary plate discipline skills that drew comparisons to those of Soto during the second half of the season? Looking under the hood, it seems like he started pressing once he started struggling. When you compare his underlying plate discipline metrics from his time in Japan to his rookie season, you can pretty clearly see where things went wrong.

In Japan, Yoshida’s low swing rates were the backbone of his approach. The qualified batter with the lowest swing rate in the majors last year was Yoshida’s World Baseball Classic teammate Lars Nootbaar (35.3%), followed by Soto (35.7%). At his peak in Japan, Yoshida approached that level of selectivity. This, combined with a low chase rate and high contact percentages on pitches in and out of the zone, was Yoshida’s recipe for success.

During the first half of last season when his plate discipline was still intact, his swing and chase rates looked similar to what he had been running in Japan. Everything trended the wrong way during the second half of the season; he became much more aggressive and started chasing pitches out of the zone at a far higher rate than he had in years.

It’s worth noting that fatigue certainly contributed to Yoshida’s struggles. The schedule in the majors is far more grueling than it is in NPB, where all the games are played in the same time zone and the longest flight takes about 3 1/2 hours. Yoshida was gassed by the end of June, right around the time he lost his approach.

When we’re analyzing a hitter’s plate discipline, looking at swing, chase, and contact rates are usually the most commonly cited metrics because they’re publicly available, but they’re a pretty blunt tool when trying to discern a hitter’s swing decisions. Thankfully, Robert Orr of Baseball Prospectus has done some fantastic work to illuminate this problem. Back in November, he introduced his SEAGER metric, which looks at expected swing or take run values and grades a player’s swing decisions based on what they actually did. It has two components: the rate of hittable pitches taken, which measures aggression; and the rate of bad pitches taken, which measures selectivity.

As you’d expect from the name of the metric, Corey Seager’s swing decisions grade out incredibly well. Juan Soto also does well via this methodology, sitting ninth in baseball in SEAGER and first in selectivity. Based on his reputation and his swing, chase, and contact rates in Japan, you’d expect Yoshida to have a high-selectivity, low-aggression SEAGER profile. That’s not exactly what the data bears out.

Yoshida’s SEAGER was quite poor because he wasn’t aggressive enough on hittable pitches to compensate for his lower-than-expected selectivity, which was roughly league average. For comparison’s sake, I included Soto’s SEAGER metrics above just to marvel at how incredible his ability to lay off bad pitches is.

When we look at the rolling graphs of Yoshida’s SEAGER components, we get a much clearer picture of what happened during his season. First his selection tendency:

We can see that Yoshida was extremely selective early in the season, up near the Soto range, but that cratered as the season went on and only barely recovered by the end of the year. His discerning eye at the plate was supposed to be the elite skill that would help him make the transition to the major leagues. That was the case for the first few months before he lost his way.

His rolling rate of hittable pitches taken doesn’t look much better:

As expected, Yoshida was pretty passive to start out the season, but he became more aggressive as he started to slump and never really recovered. Swinging at hittable pitches more often would be a good thing in a vacuum, but when taken into context with all the other things that were trending the wrong way during Yoshida’s second half, I’m not so sure it helped. Plate discipline is a fine balance between identifying bad pitches to take and being aggressive on good pitches to hit. Yoshida’s strengths seem like they’re more focused on the former, and when he became more aggressive, he threw that balance out of whack.

There were plenty of knock-on effects as Yoshida’s plate discipline deteriorated. Early on in the season, he was producing above average contact quality, helping him post a .174 ISO through the end of June. That metric dropped to .138 during the second half of the season as his contact quality collapsed along with his approach.

Despite seeing some decent results on balls in play in July, his contact quality took a steep dive in that month. Only a high BABIP and a couple of lucky home runs were able to buoy his production. His contact quality improved slightly in August, but he was hitting his batted balls at less than ideal angles, which led to far too many outs. Things got really interesting in September. His batted ball quality rebounded significantly with his highest expected wOBA on contact of the season coming during that month. Unfortunately, his actual results on those batted balls lagged well behind his expected stats. On top of that, he made far less contact that month, when he struck out 23.5% of the time. Still, it’s encouraging to see that his contact quality improved during the final month of the season, even if his discipline hadn’t recovered.

With this additional context, we can paint a pretty clear picture of Yoshida’s season. He started the season with his established approach and things were going well for him. In July, that approach started to unravel as he started swinging much more aggressively. His results on balls in play boosted his batting line that month, but everything collapsed once those hits stopped falling in. When he started slumping, he abandoned his extremely selective approach and his plate discipline never recovered. By the end of the year, his approach was completely unrecognizable from what it was in Japan.

With a full year of experience in the majors now under his belt, Yoshida has a better understanding of what to expect moving forward. His offseason training program was designed to better prepare him for the grind of a major league season, and being less fatigued should make it easier for him to return to form the next time he struggles. As he heads into his second year in the majors, he will need to lean on his excellent pitch recognition skills to sustain his success and pull him out of a slump when he goes cold. And when he inevitably scuffles again, he’ll need to remember why those skills are so critical to his success, so he doesn’t lose himself again.