The curious case of Domingo German’s curveball

On more than one occasion during the Yankees’ 8-7 loss to the Royals on Sunday afternoon, YES Network announcers John Flaherty and David Cone could be heard discussing the need for Domingo German to bury his curveball rather than leaving it elevated in the zone.

German’s lack of curveball efficiency was a small part of his worst start of the season, as the righty allowed four dingers and seven earned runs over five innings. Over his last 22 innings, German has allowed seven home runs and 25 hits, and opposing hitters have posted an OPS over .850, after managing a mark of just .470 through German’s first 38.1 innings this season. Could German’s downtick be hitters adjusting to a once unfamiliar starter, or the realization of a curveball that can’t exactly be filed under the ‘filth’ category?

First, let’s look at the positives. German showed flashes of brilliance and elite swing-and-miss stuff as early as last season, and with a lively fastball and a heightened command of his changeup, there’s no reason to think German can’t be a regularly effective starter at the major league level. But getting some more bite on that curve would help him maintain that elite level he has pitched to so far this year.

What’s interesting about German’s hook is that he uses it more than any pitch in his arsenal. He throws his curve 36.5 percent of the time, compared to 33.5 percent for his fastball and 18.3 percent for his changeup. However, despite the heavy usage, the pitch doesn’t have too much sharp movement. German’s -3.5 inches of vertical movement versus league average is among the lower marks in the league. For context, Trevor Bauer is first at 9.0 inches, and his curve had 17 percent more drop than other pitchers with a similar velocity. German’s has six percent less drop than other hurlers with a similar velocity on their breaking balls. The horizontal break on German’s curve is also among the 10 worst marks in baseball this year, meaning overall, it just doesn’t move that much, as seen in this home run by Martin Maldonado on Sunday:

As you can see in the clip above, that was once of the instances that Flaherty and Cone were talking about with regards to German’s inability to keep that curveball on the periphery of the strike zone. Turns out, that’s become a more consistent issue for German, as opposed to the brilliant command of his changeup, as you can see here:

This, unsurprisingly, has led to more hard hit balls off the the curve than the changeup. Take a look:

Given all of this information, why is German’s curveball his most utilized pitch? Well, the pitch has actually been effective thus far (opponents are slugging just .237 against his curve, but that number jumped to .875 in his last outing), but that’s been changing of late. According to Fangraphs’ pitch value metric, which uses pitch value as a way to determine how many runs a pitcher has allowed or prevented using a specific pitch, German’s curveball has dipped in value consistently over his past four outings. In his start at Tampa Bay on May 10, his curve was rated at 2.1 total runs above average. His next start dipped to 1.3, then 0.7, and his most recent outing against the Royals saw the value drop to -1.5, the lowest mark of the season.

That’s not a great trend for German, as hitters have possibly begun to realize that his curveball doesn’t have an overwhelming amount of curve to it. Still, German has two plus pitches, and if he can get some more drop on his most-used pitch, or at least locate it better, he would have a good chance at maintaining his already spectacular season so far.