Luis Castillo Has Revitalized His Season
I am not going to beat around the bush: Luis Castillo had a miserable start to the season. On Opening Day against the Cardinals, he allowed 10 runs (eight of which were earned) and recorded zero strikeouts in just three and a third innings of work. He bounced back about a week later against Pittsburgh, tossing seven innings with five strikeouts versus one walk without surrendering a run. But despite that showing, Castillo’s Opening Day struggles proved to be more than a blip on the radar for a pitcher who ranked among the top 20 in baseball over the three seasons prior to 2021. At the beginning of May, Castillo still had an ERA above six (6.07); it would not dip below that mark until his June 15 start against Milwaukee. His ERA peaked (apart from the stretch between his first and second start) at 7.61 on May 23. As of this writing, his ERA is 4.20; he has accumulated 3.0 WAR over 163 innings, placing him 26th in the majors among qualifiers.
So what has changed? Back on May 18, Justin Choi wrote about Castillo’s performance through his first eight starts, attempting to diagnose what plagued the Reds right-hander. Justin first looked at Castillo’s changeup, which had long been his most effective offering but which was generating far fewer whiffs than before. Justin found that the pitch was dropping more than it had in the past, though Castillo was still able to locate it just below the lower edge of the strike zone. The rest of Castillo’s repertoire (a sinker, four-seamer, and slider), on the other hand, was being placed right down the pipe. Justin concluded that the location of Castillo’s changeup were so different from that of the rest of his pitches that batters were either laying off the changeup or swinging at the few that landed closer to the heart of the zone.
Since Justin published his analysis, Castillo has compiled a 3.15 ERA and ranks 10th in WAR. Let’s try to locate the difference. Year-over-year, his pitch mix is largely the same:
| Season | CH | FF | SI | SL |
|---|---|---|---|---|
| 2018 | 26.2 | 36.4 | 20.9 | 16.5 |
| 2019 | 32.3 | 29.2 | 21.5 | 17.0 |
| 2020 | 30.0 | 27.1 | 25.2 | 17.7 |
| 2021 | 29.2 | 29.0 | 24 | 17.9 |
