Ryan Yarbrough has dramatically slowed his breaking ball

Ryan Yarbrough’s slider, already among the slowest in baseball, is only getting slower.

Check out how Yarbrough’s breaking ball has been operating with the passage of time, where each dot below is an appearance on the season:

The arrow indicates games over time, and the increased horizontal movement with decreasing speed is almost perfectly linear with each successive appearance. The seven dots farthest to the left are all from July and August.

And it should be noted, the change seems isolated to horizontal movement, as vertical movement remains unchanged.

How slow is this slider?

Only 22 pitchers with at least 100 innings pitched have averaged a slider velocity slower than 82 mph this season, and exactly nine have averaged a slider slower than 80 mph. Two of those pitchers are Chris Sale and Dallas Keuchel, while Yarbrough is the slowest at an average of 77.1 mph.

Yarbrough has been steadily increasing his slider usage throughout the year in general, and particularly against same handed hitters (Please note: in the charts below, August only has one appearance from Yarbrough and therefore has higher variance).

And with that increase has come a consistently improving Batting Average Against . . .

Along with a notably improving whiff rate against left handed hitters in particular, who have surprisingly given Yarbrough trouble this year (.325 wOBA allowed):

Brooks Baseball calls this breaking ball a slider, which seems correct, and there’s also a good chance that the solitary curveball on the graphs above was one of his “sliders” as well that just slipped past the editors.

The MLBAM classifications call this breaking ball a curve, which means that Yarbrough doesn’t appear on this fangraphs leaderboard. But right now, in this more recent section of the season, his breaking ball is averaging approximately eight inches of horizontal movement, which would rank 15th among the sliders of all pitchers with 30 IP this season.

Among starters, that ranks Yarbrough alongside Corey Kluber in movement (although, to be fair, Kluber’s breaking ball sits in the low 80s), and only starter Mike Clevenger has a slider averaging nine-plus inches of horizontal movement among starting pitchers.

Slider quality is a complex thing to talk about, because there is such a wide range in the types of sliders. It’s a combination of movement, velocity, and deception. Generally, the goal is to throw hard for the movement you have (Chris Archer) or have lots of movement for the speed you throw (Sergio Romo). With Yarbrough improving his movement while dropping his velocity, the overall affect may depend on interactions with his other pitches, but so far the change appears to be a positive one.

By stretching the pitch out, Yarbrough is creating a greater velocity separation between his slider and his fastballs (four-seam and cutter). Despite the bad outing for his cutter you might have spotted above in his most recent appearance, this may give Yarbrough a more effective way of messing with hitter timing. And at those speeds, how could hitters not be thrown off?

Is this sustainable?

In order to achieve the change in speed of his breaking ball, there is a valid concern that Yarbrough might be slowing his delivery to create the difference. If that were the case, with time, it’s possible batters would pick up on any slight difference and know a breaking ball is coming.

Now, whether hitters know the pitch is coming or not is less relevant than whether they can make meaningful contact—but for most pitchers, deception matters.

Check out his most recent outing on August 5th against the White Sox, and try not to look at the pitch speeds clocked when they reach the glove and focus on his delivery. Below is strikes one, two, and three from a swinging K of left-handed power hitter Daniel Palka:

The pitch on the left is a fastball, the other two are breaking balls. Do you see a meaningful difference in his delivery?

The final pitch (right) varies in that it includes a bit of a dance off the mound, as it was a 3-2 strikeout for the second out in the top of the seventh, with Yarbrough nearing the end of his night. Other than that, I see no variation, and for that reason I would say this improvement on his breaking ball can stick.