Yoshinobu Yamamoto struggled a bit on Sunday morning. With storms looming in the Cincinnati area, he was only able to make it through five innings, getting touched up for four runs on six hits and a pair of walks. It's only his second loss on record, though, and he did generate eight strikeouts against a Reds team rather known for it.
There was plenty of bad luck involved. The Reds had a .462 BABIP against Yamamoto, who actually posted a FIP of 1.13 in the start. So it's one where the box score doesn't tell the full story on its own.
However, questions surrounding his pitch mix continue to exist.
On the season, Yamamoto has thrown six different pitches, all to varying degrees. The four-seamer has been ol' reliable, while he's also thrown a curve, splitter, cutter, sinker, and slider, according to Baseball Savant. The slider, in particular, appeared suddenly on May 1st. The sinker didn't manifest itself as a regular pitch until his next start on May 7th.
It's a rather puzzling picture, as there was a stretch where it looked like the mix was beginning to stabilize. From April 25th through May 20th, Yamamoto went four-seam/splitter as his primary offerings. The curve was his third pitch, but the sinker & slider each started to appear with a little more regularity more recently. On May 20th, he threw the curve, sinker, and slider all at virtually the same rate.
On Sunday, though, Yamamoto threw the curve almost as much as the four-seam. The splitter took a massive backseat, while the sinker & slider fell behind even his seldom-used cutter in terms of usage.
Of course, none of this is meant to read as criticism of Yamamoto. Adjustments are being made on the fly in his first full season at the big league level. Pitches like the slider & sinker are being incorporated as he goes. And there's likely a 'feel' component in here that's going to change in any given start.
Pitch mix is going to vary each start depending on feel. That's true of any pitcher. It's especially true of one making the adjustment to Major League Baseball. One thing that could be crucial for Yamamoto, though, is determining if the slider & sinker are usable pitches, worthy of regular incorporation.
Ultimately, though, this isn't a concerning element leading to his demise in starts like Sunday. That was a stroke of bad luck above all. For us as observers, it lends itself to a certain fascination, as it's allowing us to see adjustments happening on the fly, while attempting to predict what he's going to throw next.