What’s wrong with Yu Darvish? It’s an existential question that I wish I had an absolute answer to, but the reality is that baseball never has absolute answers. What I can tell you is that Darvish’s issues might stem from a variety of changes to his slider. He’s throwing that pitch to the opposite side of the plate and it looks very different overall.
Darvish’s slider location has changed
One reason Darvish was successful as a Ranger and Dodger was because he could pinpoint exactly where he wanted to throw the slider. For instance, Darvish owned batters in 2017 by locating on the outside portion of the plate to righties.
2017 slider heat map (from catcher’s perspective)
But as a Cub, Darvish has gone away from throwing outside sliders and instead is throwing more to the inside part of the zone. Whether this is intentional or not is unknown. It could just be he can’t get a feel for the pitch.
Darvish’s slider looks different
Prior to joining the Cubs, Darvish’s slider generated the most horizontal movement in MLB among right-handed starters. The sharp-cutting pitch was also thrown with more dropping action than 93 percent of MLB pitchers. In other words, Darvish’s slider might’ve been the nastiest breaking pitch on the planet.
Now, however, Darvish is throwing sliders with about 20 percent less horizontal movement and 70 percent less drop. We can’t say for certain, but it’s probably because he’s throwing the pitch 3 mph faster this year than last (2017: 82 mph, 2018: 85 mph).
Darvish’s slider horizontal movement (smaller numbers means less cutting action)
Darvish’s slider vertical movement (negative numbers means more dropping action)
Darvish’s slider is getting rocked
Perhaps because he is throwing sliders to a different part of the zone and with less movement, batters are crushing Darvish’s breaking pitch for tons of extra-base hits. For instance, the Japanese righty surrendered only a .146 isolated power (ISO) in 2017, but he has given up a .303 ISO so far in 2018. Hitters are making the most of their contact when barreling up.
Tying it all together
Darvish wrote in his blog that he has been trying to throw sliders that drop more. So maybe the Cubs have already identified the issue, who knows. And this is only one observation. There could be several other areas of Darvish’s game that are off but are not visible to either the naked eye, even with the help of some digital sleuthing.
But we can see and say without a doubt that Darvish is throwing sliders to a different part of the plate with much less movement and higher velocity. It’s almost like he’s throwing a different pitch.