Reason for Yoshinobu Yamamoto's struggles is painfully obvious

Yoshinobu Yamamoto is dealing with the unbearable weight of massive expectations. They're not unearned nor unjustified; despite some ridiculous complaints about the size of his contract when he signed with the Dodgers, being the best pitcher in NPB by a mile (a three-time Triple Crown winner in consecutive seasons) warranted a large payday in his MLB transfer. That payday and his NPB record then understandably translated into pressure to be great as soon as he took a major league mound.

It hasn't quite gone that way, though. Yamamoto has made five starts so far, three of which have been rough, and four of which have resulted in loses for the Dodgers. In his latest outing on April 19, he pitched six innings (the most of any start so far), and gave up seven hits and four runs, including a home run.

As a result, his Baseball Savant page is filled with a lot of blue where we'd expect (or hope) to see red. Further down, the not-so-secret behind his struggles is plain as day: his fastball has been flying right down the middle of the plate into hitters' sweet spots.

The reason behind Yoshinobu Yamamoto's early season struggles are clear as day

Yamamoto's fastball, which he uses 37% of the time, has a brutal .355 batting average and .710 slugging against. The rest of his pitches — mostly a curveball, split finger popular with Japanese pitchers, cutter, and a slider he's only thrown once — have a collective .191 batting average against. The split finger is his most devastating by far, with a .115 XBA, and has racked up the most strikeouts of any of them. On the other hand, the fastball accounts for two of the three home runs Yamamoto has given up, as well as five of six doubles.

Clearly, the problem is location on the fastball. It's unlikely that a pitcher of Yamamoto's caliber thinks that he can always get away with sneaking one by hitters when they're coming straight down the center, so it probably just hasn't been finding the right spots.

It seems like a problem with a simple solution, but it's also been persistent enough that it's effectively sunk the majority of Yamamoto's starts. Dodgers hitters not backing him up does account for some of this, it feels important to add, but Yamamoto giving them uphill battles to fight when he gives up multiple runs in early innings is hardly the way to put the Dodgers in the right place to win.